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Biology Exam 4

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invertebrates
animals that lack a backbone
example of invertebrate
Christmas tree worm
what accounts for ninety percent of known animal species?
invertebrates
what has produced diversity of forms
adaptation to the varied environments.
Sponges are ____ animals that lack ___ tissues
basal; true
Porifera
sponges
sponges are
monophyletic
what are the simplest of animals?
sponges, and they are sedentary, sometimes mistaken for plants by the ancient Greeks
sponges are what kind of feeders?
suspension feeders
suspension feeders-
capture food particles suspended in the water that passes through the body (sac perforated with pores)
where is water drawn in the body?
the pores, and into a central cavity, the spongocoel
where does the water flow out the body?
through a larger opening called the osculum
sponges are what kind of animals?
basal animals
basal animals
represent a lineage that originates near the root of the phylogenetic tree of animals
sponges lack
true tissues, groups of similar cells that act as a functional unit and are isolates from other tissues by membranous
a sponge body containes
several different cell types
the interior of the spongocoel are
flagellated choanocytes, or collar cells
what are collar cells named for?
finger like projections that form a collar around the flagellum
these cells engulf bacteria and other food cells by
phagocytosis
what supports the evidence that animals evolved from a choanoflagellate-like ancestor
similarity between choanoctyes and cells of choanoflagellates
the body of a sponge consists of
two layers of cells separated by a gelatinous region called the mesophyl
what allows gas exchange and waste removal ?
both cell layers are in contact with water, and diffusion across the membrane
what are other tasks performed by?
amoebocytes- named for their psuedopodia
functions of amoebocytes
take up food from surrounding living water and from choanocytes, digest it, and carry nutrients to other cells. can also manufacture tough skeletal fibers within the mesophyl, made from calcium carbonate or sillica
other sponges produce more flexible fibers composed of
a protein called spongin- bath sponges
amoebocytes are capable of
becoming other types of sponge cells
becoming other types of sponge cells enables it to adjust its shape
in response to physical change in the environment, direction of water currents
hermaphrodites
each individual functions as both male and female in sexual reproduction by producing sperm and eggs
sequential hermaphroditism
they function first as one sex and then the other
where do sponge gametes arise?
choanocytes or amoebocytes
eggs reside in
the mesophyll
sperm are carried out of the sponge by
the water current
what results from some of the sperm being drawn into neighboring individuals?
cross fertilization
where does fertilization occur?
Mesophyl
in the mesophyl
zygotes develop into a flagellates, swimming larvae that disperse from the parent sponge
Cnidarians are an ancient phylum of
eumentazoans
wat clade do all animals except sponges and a few other groups belong to?
eutmetazoa
clade with animals with true tissues?
eutametazoa
one of the oldest lineages in this clade is the phylum
cnidaria
cnidarians have diversified into a wide range of sessile and motile forms including:
hydras, corals, and jellies
basic body plan of a cnidarian
sac with a central digestive componet, the gastrovascular cavity
the single opening to the gastrovascular cavity functions as
both the mouth and the anus
two variations of the body plan of cnidarian:
the sessile polyp and the motile medusa
polyps
cylindrical forms that adhere to the sunstrate by the aboral end of their body (the end opposite of the mouth) and extend their tenticles, waiting for prey.
examples of polyp:
hydras and sea anemones
medusa
resembles a flattened, mouth-down version of the polyp. it moves freely in the water by a combo of passive drifting and contractions of its bell-shaped body
medusae include
free swimming jellies
where do the tentacles of a jelly dangle from?
the oral surface, which points downward
some cnidarians only exist as ___, others exist as ____
polyps or medusae; both a polyp stage or a medusae stage
cnidarians are ___ that often use ____ to capture prey and push the food into the ____
carnivores; tenticles arranged in a ring around their mouth; gastrovascular cavity.
what is secreted into the cavity?
enzymes, breaking down the prey into a nutrient rich broth
cells lining the cavity do what?
absorb these nutrients and complete the digestive process
any undigested remains is expelled through the
mouth/anus
the tenticles are armed with
batteries of cnidoctytes, function in defense and prey capture
what is uniqe to cnidarians?
cnidocytes
cnidcytes contain
cnidae, capsule like organelles that are capable of exploding outward and that give phylum Cnidaria its name
specialized cnidae
nemotocysts
stinging thread that can penetrate the body wall of cnidarian's play is contained in the
nemoctysts
other kinds of cnidae
have long thread that stick to or entangle small prey that bump into the cnidarian's tentacles
simplest formes of nervves and tissues is in?
cnidarians
what have bundles of microfilaments arranged into contractile fibers
cells of the epidermis (outer layer); gastrodermis (inner layer)
gastrovascular cavity acts as a
hydrostatic skeleton against which the contractile cells can work
when a cnidarian closes its mouth
the volume of its cavity is fixed and contraction of selected cells causes the animal to change shape
movements are coordinated by a
nerve-net
why can cnidarian detect and respond to stimuli from all directions?
they have no brain, and the noncentralized nerve net is associated with sensory structures that are distributed around the body.
phylum cnidaria is divided into four clades:
hydrozoa, scyphozoa, Cubozoa and anthozoa
hydrozoans alternate betweeb
polyp and medusa forms
when an environment is favorable
a hydra produces asexually by budding
when conditions deteriorate
hydras can produce sexually, forming resistant zygots that remain dormant until conditions improve
prominante stage of scyphozoans
medusa
where do the medusa of most species live
plankton, as jellies
many schyphozoans go through a stage of being
small polyps during their life cycle
cubozoans
have a boxed shaped medusa stage
cubozoans also have
complex eyes imbedded un the fringe of their medussae, strong swimmers
anthozoans
occur only as polyps
corals live in
solitary or colonial forms
form symbioses with algar
secrete a hard externaml skeleton of calcium carbonate
each polyp genetation does what
builds on the skeletal remains of earlier generations contructing rocks
!!the skeletons are what?
coral!!
lophotrochozoans have the widest range of
animal body forms
the vast majority of animal species belongs to the clade
Bilatera
bilaterian animals members exhibit
bilateral symmetry and triploblastic development
most bilaterians have a
digestive tract with two openings (a mouth and an anus) and a coelom
when did the most recent common ancestor of living bilaterians exists?
late Proterozoic eon
three major clades of bilaterally symmetrical animals are:
Lophotrochozoa, Ecdysozoa and Deuterostomia
Lophotrochozoa's name comes from
features found in some of its members
three features of lophotrochozoas
1) some develop a structure called a lophophore (crown of ciliated tentacles that functions in feeding)
2) some go through a distinctive stage caked the trochophore larva
3) some have none of those features
lophotrochozoans are the most
diverse bilaterian clade in terms of body plan
where does the diversity in form reflected in?
the number of phyla classified in the group (18)`
six diverse lophotrochozoan phyla
flatworms, rotifers, ectoprocts, brachiopods, molluscs, and annelids
where do flatworms live?
marine, fresh water and damp terrestrial habitats
flatworms include many ___ species such as
parasitic species such as flukes and tapeworms
why are flatworms named this?
they have thin bodies that are flattened doesoventrally
platyhelminth
flat worm
flatworms undergo ___ development
triploblastic development
flatworms are
acoelomates (animals that lack a body cavity)
what does the flatworm's flat shape do?
places all their cells slose to the water in the surrounding environment or in their gut
how does elimination and gas exchange occur
diffusion across the body surface
flatworms simple excretory apparatus functions in
maintaining osmotic balance with the surroundings
the apparatus consists of
protonephridia
what are protonephridia?
networks of tubules with ciliated structures called flame bulbs that pull fluid through branched ducts opening to the outside
most flatworms have a gastrovascular cavity with how many openings?
one!!!
flatworms separated into two lineages:
Catenilida and Rhabditophora
Catenilidia
small clade about 100 flatworm species, reproduce by budding at the posterior end; offspring can produce own buds before detatching from the parent, thereby forming a chain of two to four genetically identical individuals "chain worms"
Rhabditophora
diverse clade about 20000 freshwater and marine species- free living and parasitic members
free living rhabditophora
predators and scavengers in a wide range of marine habitats
best known members of free living rhab. are
freshwater species in the genus Dugesia, commonly called planarians
planarians are abundant where? and they prey on..
unpolluted ponds and streams; smaller animals or feed on dead animals
how do planarians move?
using cilia on their ventral surface, gliding along a film of mucus they secrete
planarians head
equipped with a pair of light sensitive eyespots and lateral flaps that function mainly to detect specific chemicals
planarians nervous system
more complex and centralized than the nerve nets of cnidarians
some planarians reproduce?
asexually through fission
decribe the fission of planarians
parent constricts roughly in the middle of its body, separating into a head in and a tail end; each end then regenerates the missing parts; sexual rep also occurs
planarians are
hermaphrodites and mates typically cross fertilize each other
how do half of the known species of rhabditophorans live
as parasites in or on other animals, many have suckers that attach to the internal organs or outer surfaces of the host animal
in most species, what helps protects the parasites within the hosts?
a tough covering
what do reproductive organs occupy?
nearly the entire interior of these worms
two ecologically important subgroups of parasitic rhabditophorans:
trematodes and tapeworms
reproduction of trematodes
alternating sexual and asexual stages
many trematodes require an
intermediate host in which larvae develop before infecting the final host where the adult worms live
infectuois tremotodes are called
blood flukes
how does a blood fluke create a partial immunological camouflage for itself?
mimicking the surface proteins of its hosts and releases molecules that manipulate the hosts immune systems into tolerating the parasite's existence
tapeworms
large and diverse clade of parasitic rhabditiphorans
where do the adult tapeworms live?
mostly inside vertebrates, including humans
in many tapeworms, the anterior end, or scollex, is armed with
suckers and often hooks that the worm uses to attach itself to the intestinal lining of the host
how do tapeworms get nutrients without a mouth and vascuar cavity??
absorb nutients released by digestion in the host's intestine.. absorption occurs across the tapeworm's body surface
what is posterior to the scolex?
a long ribbon of units called proglottids- little more than sacs of sex organs
what happens after sexual reproduction?
proglottids loaded with thousands of fertilized eggs are released from the posterior end of a tapeworm and leave the hosts body in feces
clade Ecdysozoa includes animals that do what?
shed a tough external coat (cuticle) as they grow.
molting
ecdysis
two largest ecdysozoan phyla
nematodes and arthopods
nemotodes
roundworms
nematodes do not have..
segments bodies, they have cylindrical bodies.
describe the cylindrical body of the nematode:
a fine tips at tip at the posterior end and to a blunter tip at the anterior end
a nematode's body is covered by a
tough cuticle (type of exoskeleton)
what happens to the cuticle periodically?
it periodically sheds its old cuticle and secretes a new, larger one.
nematodes have a ___ but they lack a ___
alimentary canal; circulatory system
how are nutrients transported through the body of a nematode?
via fluid in the pseudocoelom
the body wall muscles of a nemotode are ___
longitudinal
what does nematodes muscle contraction produce?
thrashing motion
reproduction of nematode
sexually, by internal fertilization
decomposition and nutrient cycling are..
important roles of nematodes
nematode species that humans are hosts to
pinworms and hookworms
what redirects some of the cellular functions of their host and thus envade their immune systems
parasitic nematodes
plant host in regards to parasitic nematodes?
inject plant hosts with molecules that induce the development of root cells, supply nutrients to the parasites
infected muscle cell releases signals that
promote thte growth of new blood vessels which then supply nematode with nutrients
arthopods
billion billion species 10e18, most = insects
what contributes to success of arthopods?
body plan: segmented, hard exoskeleton, jointed appendages
fossils of arthopods
Cambrian explosion
lopods
arthropods may have evolves, body segments identicle, trilobites (earliest arthopods) also showed little variation
arthopods today have
two unusual Hox genes
Hox genes influence
segmentation
arthopod body plan diversity did NOT arise from aquisition of new Hox genes, it arose by
changes in the sequence or regulation of existing Hox genes
structures in arthropods are
jointed and come in pairs
exoskeleton of arthropod is made of
layers of protein and polysaccharide chitin
the cuticle can be __ over some parts of the body and ___ over other parts
thick and hard; paper thin
rigity of exoskeleton serves what purpose
protection, provides points of attachment for the muscles that move the appendages
arthopod cannot grow without
occasionally shedding its exoskeleton and producing a larger one
what is energetically expensive
molting process
when does the arthopod stop being vulnerable to predation
after its new, soft exoskeleton hardens
later in time
certain arthopods were able to live on land
when did arthopods diversify on land
paleozoic
what kind of sensory organs to arthopods have?
well-developed
circulatory of arthropods
open- fluid called hemolymph is propeled by the heart through short arteries and then into spaces called sinuses surrounding the tissues and organs, hemolymph reenters heart
hemocoel
hemolyph filled body sinusses- not part of the coeleom
coelem in arthropod embryo
becomes much reduced as development progresses
hemocoel
main body cavity in adult arthropods
open circulatory systems of molluscs and arthropods arose how?
independently
gas exchange organs in arthropods
diffusion of respiratory gases in spite of exoskeleton
arthropods consist of four major lineages that diverged early in evolution of the phylum:
cheliceratres, myrispods, hexapods, crustaceans
chelicerates have
clawlike feeding appendages called chelicerae- pincers or fangs
chelicerates have an anterior_ and posteror_
cephalothorax; abdomen
what do chlicerates have and what do they lack
simple eyes; antennae
earliest chelicerates were
eurypterids (water scorpions), most marine ones are extinct other than sea spiders, horseshoe crabs
modern chelicerates that includes scorpions, spiders, ticks, mites
arachnids
ticks and mites are
parasitic arthropods
arachnids have a
cephalothorax with six pairs of appendages, chelicerae and a pair called pedipalps- walking legs
what do spiders use their fang like chelicerae for?
poison glands to attack prey.
how is gas exchange carried out in most spiders?
book lungs, stacked plate-like structures contained in an internal chamber
what enhances exchange in O2 and CO2 between hemolymph and air
extensive surface area of these respiratory organs
unique adaptaion of spiders
ability to catch insects by constructing a bed of silk
(liquid protein secrete by abdominal glands)
how is silk spun?
organs called spinnerets into fibers that then solidify
evidence that web spinning is inherited?
perfect on the first try
balooning
exporting silk into the air and let themselves be tranported by wind
myriapods examples
millipedes and centipedes
myriapod head has
a pair of antennae and three pairs of appendages modified as mouth parts, including jaw like mandibles
millipedes have a large number of what?
legs
trunk segment in millipedes
formed from two fues segments and bares two pairs of legs
what do millipedes eat?
decaying leaves
centripedes are
carnivores
each segment of a centripede's trunk region has
one pair of legs
what else do centripedes have?
poisonous claws on trunk that paralyze prey and aid in defense
insect fossils
Devonian period
insect flight evolved when?
Carboniferous and Permian periods, this increased insect diversity
flight
escape many predators, find food mates, disperse to new habitats faster than an animal that must crawl about on the ground
many insects have what the emerge from
one or two pairs of wings that extend from the dorsal side of the thorax
why can insects fly without sacrificing any walking legs
bc the wings are extensions of the cuticle and not true appendages
what do many insects undergo during development??
metamorphosis
incomplete metamorphosis
the young resemble adults but smaller and have many different boy proportions and lack wings, lymph undergoes a series of molts, each time looking more like adult
complete metamorphosis
larvae stages- eating and growing (caterpillar, maggot, grub)
compare larvae stage to adult stage
completely different
reproduction of insects
sexual
adults insects come together ??
bright colors (butterflies), sounds (crickets), odors (moths)
sperm deposited how
directly into the female's vagina at time of copulation
where is sperm stored in female?
spermatheca
how many times does an insect mate
once n a life tiem
who do insects compete with for food?
humans
crustaceans have remained in what kind of environments?
marine and freshwater
what do you think of when talking about crustaceans?
highly specialized appendages!!!!!
anterior appendages
antennae (only arthropods with two pairs crust)
mouth parts
three or more pairs of appendages
where are walkign legs present on crustaceans?
thorax, and abdomen (unlike insects)
when can a lost appendage be regenerated?
molt
small crustaceans exchange gases through
thin areas of cuticle
larger ones have
gills, nitrogenous wastes also diffuse though cuticle
what regulates salt balance of hemolymph
pair of glands
sexes are what in crustaceans?
separate
what does male use to transfer sperm
pair of abdominal appendages into rep pore during copulation
most crustaceans go through one or more
swimming larvae stages
isopods (large group of crust)
terrestrial, freshwater and marine speices
decapods
large: lobsters, crayfish, crab, shrimp; seafood
what is cuticle of decapods hardened by
calcium carbonate- portion that covers dorsal side of cephalothorax forms a sheild called carapace
planktonic crustaceans inclide
copepods- grazers that feed upon algae, others are predators that eat small animals (including smakker copepods) krill
larvae of many larger crustaceans are
planktonic
barnicles
group of sessile crustaceans whose cuticle is hardeend into a shell containing calcium carbonate
barnicles natural adhesive
stong as some synthetic glues
how do barnicles feed?
extending appendages from their shell to strain food from the water
echinoderms and chordates are
deuterostomes, closely related
deuterostomia clade is what kind of animals?
bilaterian
echinoderms and chordates share features such as
radial cleavage and formation of the anus from the blastopore
deuterostomia is defined primarily by
DNA similiarities
what is it not defined by?
developmental similarities
echinoderms are
slow moving or sessile marine animals (sea stars)
echinoderms have a __ that covers____
thin epidermis; endoskeleton of hard calcareous plates
most echinoderms are prickly from
skeletal bumps and spines
what is unique to echinoderms?
water vascular system- canals branching into extensions called tube feet that function in locomotion and feeding
sexual reproduction of echinoderms usually involves
separate male and female individuals that release their gametes into the water
where do the parts of most adult echnoderms radiate from?
the center, often as five spokes
echinoderm larvae have
bilateral symmetry, sym of adult echinoderms is not truly radial
living echinoderms are divided into 5 clades:
asteroidea, ophiuroidea, echinoidea, crinoidea, holothuroidea
asteroidea: sea stars and sea daisies, have
arms radiating from a central disk; the undersurfaces of the arms bear tube feet
tube feet can attach or detach to a
substrate
star adheres to
rocks, ect
the base of tube feet has
a flattened disk that resembles a suction cup
grippingaction results from
adhesive chemicals, not suction cup
what do sea stars use their tube feet for?
grasp prey
digestive process of sea star involves
turning stomach inside out, dig system secretes juice that digests the mollusc within its own shell, stomach is brought back inside where digestion is completeted
regeneration
regrow lost arms, even grown entire body from single arm if part of the central disk remains attached
another small group in asterioda
sea daisies (armless)
sea daisy body
disk shaped, five sides, ringed with small pines, absorb nutrients throufh a membrane that surrounds the body
ophiuroidea: brittle stars have
a distinct central disk and long, flexible arms
how do brittle stars move
lashing their arms in serpentine movements
the base of the brittle star lacks the
flattened disk found in sea stars but it does secrete adhesive chemicals, so brittle stars also can use their tube feet to grip substrates
echinoidea: Sea urchins and sand dollars
these have no arms, but five rows of tube feet that function in slow movement
sea urchins have muscles that
pivot their long spines, aid in locomotion as well as protection
mouth of a sea urchin
ringed by highly complex, jaw-like structures well adapted to eating seaweed
sea urchins are roughly ___ while sand dollars are ___
spherical; flat disks
crinoidea: sea lillies and feather stars live
attached to the substrate by a stalk; crawl about using their long, flexible arms
holothuroidea: sea cucumbers
lack spines and their exoskeleton is much reduced
sea cucumbers are
elongated in their oral-aboral axis, giving them the shape for which they are named
chordates are
bilaterally symmetrical coelmates with segmented bodies
chordates have a __ and ___
notochord; dorsal, hollow nerve chord
vertebrates are members of the phylm
chordata, chordates
chordates belong to clade of animals known as
deuterostomes
best known deuterostomes are
echinoderms
two groups of invertebrate deuterstomes that are more closely related to vertebrates than to other invertebrates
cephalochordates and urochordates
four key characters of chordates:
a notochord; a dorsal, hollow nerve chord; pharyngeal slits or clefts; a muscular, post- anal tail
some of these traits are only shown during embryonic development
chordates are named for
a skeletal structure, the notochord present in all chordate embryos and adult chordates
notochord is
longitudinal, flexible rod located between the digestive tube and nerve cord
notochord provides
skeletal support throughout most of the length of the chordate, flexible structure muscles can use for swimming; jointed skeleton develops around the ancesral notochord, adult only retains remnants of embryonic one
nerve chord of a chordate develops from a
plate of ectoderm that rolls into a tube located dorsal to the notochord.
what is unique to the chordates?
the resulting dorsal, hollow nerve cord
what does the nerve cord of a chordate develop into
the central nervous system: the brain and the spinal chord
where does the digestive tube of a chordate extend from
the mouth to the anus
region just posterior to the mouth is the
pharynx
a series of pouches seperated by grooves froms where?
along the sides of the pharynx
grooves
pharyngeal clefts- develp into slits that open to the outside of the body
what do the pharyngeal slits do
allow water entering the mouth to exit boy withough passing through entire digestive tract
pharyngeal slits function as
suspension feeding devices in many invertebrate chordates
in vertebrates
the structures that support them have been modifies for gas exchange and are known as gill slits
where does the tail of a chordate extend?
posterior to the anus, greatly reduced during embryonic development
what does the chordate tail contain
skeletal elements and muscles
these skeletal elements and muscles help
propel many aquatic species in the water
Lancelets are the most
basal (earliest diverging) group of living chordates
where do lancelets get their name
bladelike shpe
what do lancelets do as larvae?
develop a notocjord, a dorsal hollow nerve cord, numerous pharyngeal slits and a post-anal tail
the lancelets larvae feed on
plankton in the water collumn, they trap plankton as they sink
what draws seawater into the lancelets mouth?
cilia
what removes food paticles as the water passes through the slits?
a net of mucus secreted across the pharyngeal slits, trapped food enters the intestine
lancelets have the swimming mechanism of a
fish
swimming of lancelets
coordinated contraction of muscles arranged like rows of chevrons (<<<<) along the sides of the notochord flexes the notochord, producing side to side undulations that thrust the body forward
what is evidence of the lancelet's segmentation
serial arrangement of muscles- develop from somites
tunicates are more closely related to _ than _
other chordates than are lancelets
when are chordate characters most apparent in tunicates?
during the larval stage, which may only be a few minutes
what does the larva do in tunicates?
uses its tail muscles and notochord to swim through water in search of a suitable substrate on which it can settle; guided by cues it recieves from ligh and gravity sensitive cells
where does a tunicate fraw in water
an incurrent siphon, then the water passes tjrough the phayngeal slirs into a chamber called the atrium and exits through the excurrent siphon by a mucus net and transported by cilia to the esophogous
craniates are chordates that
have a head
the origin of the head (brain, eyes, skull) enabled chordates to
coordinate more complex movement and feeding behaviors
why do craniates possess tow or more sets of Hox genes (lanceletes and tunicates have only one)
gene duplication
what led to more genetic diversity?
divergence of sequences in the duplicate genes
what is a feature unique to craniates?
neutral crest- a collection of cells that appears near the dorsal margins of the closing neural tube in an embryo
neutral crest cells disperse throughout the body where they
give rise to a variety of structures, including teeth, some of the bones and catilage of the skull, the inner layer of skin, neurons ect
in aquatic craniates, the pharyngeal clefts did what?
evolves into gill slits
gill slits are associated with muscles and nerves that allow water to be pumped through the slits. this pumping can
assist in sucking in food and facilitates gas exchange
Craniates are more what than what?
more active than lancelets and tunicates
what does this say about craniates
they have a higher metabolic rate and a much more extensive muscular system
how do muscles lining the digestive tract aid digestion?
by moving food through the tract
Craniates also have a
heart with two chambers, rbc with hemoglobin, and kidneys that remove waste products from the blood
what is the most basal group of the craniates
myxini, hagfishes
what do hagfishes have?
skull made of cartilage, but they lack a haw and vertebrae
how do hagfishes swim?
snakelinke, using segmented muscles
hagfishes mouth contains
toothlike formations made of the protein keratin
rows of slime glands on a hagfishes flanks secrete a substance the absorbs water, forming what?
a slime that may resulse other scavengers when a hagfish is feeding
the slime coats the gills of an attacking fish, sending it into
retreat or even suffocating it
vertebrates are
craniates that have a backbone
vertebrates becaome more efficient at two essential casts
capturing food and avoiding being eaten
vertebrates underwent another gene duplication involving
a group of transcription factor genes called the Dlx family
what did aquatic vertebrates aquire?
dorsal, ventral and anal fins stiffened by bony structures called fun rays
faster swimming was supported by other adaptations including:
a more efficient gas exchange system in the gills
what are the most basal lineage of living vertebrates?
lampreys
most lampreys are
parasites
how do they feed?
clamping their round, jawless mouth onto the flank of a live fish
skeleton of lampreys is made of
cartilage
lamprey cartilage contains
no collagen, unlike other cartilages. instead it is a stiff matrix of other proteins
lampreys also have a
flexible sheath around their rod'like notochord, cartilaginois projections related to vertebrae extend dorsally, partially enclosing the nerve cord.
conodonts were
slender, soft bodied vertebrates with prominent eyes controlled by numerous muscles. large eyes
hooks in mouth
tissues that were mineralize- composed of calcium (rigitiy)
additional innovations of vertebrates emerged during
Ordovician, Silurian and Devonian periods
these vertebrates had
paired fins and as in lampreys, an inner ear with with two semi circular canals that provided a sense of balance
armor
protection from predators (spines)
vertebrates skeleton evolved initially as
a structure made of unmineralized cartilage
hypothesis about mineralization
mineralization of the vertebrate body may have begun in the mouth and later was incorporated into protective armor
Gnathostomes are
vertebrates that have jaws
gnasthoso,es imcludes
sharks and relatives ray finned fish, lobe finned fish, amphibians, reptiles and mammals
gnathosomes are named for
their jaws
jaws
hinged structires especially with the help of teeth enable gnathosomes to grup food items firmly and slice them
according to one hyp: jaws evolved by
modification of the skeletal rods that previosly supported the anterior phayngeal gill slits
the remaining gill slits remained as
sites of respiratory gas exchange with the external environment
other derived characteristics besides jawss
ancestors underwent additional duplicatuon of Hox genes- single set in early chordates became four, entire genome appears to be duplicated
gnathsome forebrain is
enlarged compared to that of other craniates
lateral line system
organs that form a row along each side of the body and are sensitive to vibrations in the surrounding water
gnathosome successs
paired fins and tail allowed them to swim efficiently after prey and their jaws enable them to grab prey or simply bite off chunks of flesh
earliest gnathosomes include extinct lineage of armored vertebrates known as
placoderms (plate skinned)
other groups of jawed vertebrates arre collectively called
acanthodians, emerged roughly at the same time and radiated durinf the Silurian and Devonian Periods
420 mllion years ago, they diverged into 3 lineages of jawed vertebrates that survive today:
chondryctians, ray finned fishes, and lobe fins
sharks, rays, ect
most successful vertebrate predators in the ocean
they belong to the clade
Chondrichthyes (cartilage fish)
chondrichthyans have a skeleton composed of
predominateluy cartilage, though often impregnated with calcium
mineralization of vertebrate skeleton haad already begun before...
the chondrichthyan lineage branched off from other vertebrates
traces of bone can also be found in
living chondrychthyans- in their scales at the base of their teeth and in some sharks in a think layer on the surface of their vertebrae
largest and most diverse group of chondrichthyans
sharks rays skates
shark's powerful movemnt of trunk
and tail pin propel them forward
dorsal fins function mainly as
stabilizers
paired pectoral (fore) and pelvic (hind) fins are important for
maneuvering
a shark gains bouyancy by
storing a large amount of oil in its huge liver
shark is more
dense than water so if it ist swimming it will sink
continual swimming ensured that
water flows into the shark's mouth and out through its gills, where gas exchange occurs
when resting,, they use muscles of their jaws and pharynx to
pump water over the gills
the largest sharks and rays are
suspension feeders that consume plankton
most sjarks are
carnivores thta swallow their prey whole or use jaws to tear flesh from animals too large to swallow in one peice
sharks have several rows of
teeth that gradually move to the front of the mouth as old teeth are lost
digestive tract of of many sharks is proportionally
shorter than that of many other vertebrates
within the shark intestine is a
spiral valve, a cork screw shaped ridghe that increases surface area and prolongs the passage of food through the digestive tract
acute senses
sharp viosn but cannot distinguish colors, nostirls open into dead end cups (olfactory) not for breathing
how does sound reach a shark
through water and the animal's entire body transmits the sounf to the hearing organ of the middle ear (no eardrums)
how are shark eggs fertililzed
internally, male has a pair of claspers on pelvic fins transfers sperm into reproductive figestive tract of female
oviparous
lay eggs that hatch outside the mother's body; release eggs after encasing them in protective coats
ovoviviparious
retain fertilized eggs in the oviduct; nourished by the egg yolk, embryos develop into young that are born after hatching within the uterus
viviparous
young develop within the uterous and obtain nourishment prior to birth by recieving nutrients from the mother's blood through yolk sac placenta; rep ttract empties along with excretory system and dig tract into the cloaca, a common chamber that has a single opening to the outside
rays are closely related to __ but have
sharks, different life styles
MOST RAYS ARE
BOTTOM DWELLERS THAT FEED BY USING THEIR JAWS TO CRUSH MOLLUSCS AND CRUSTACEANS
FLATTENED WHAT
SHAPE AND USE ENLARGED PECTORAL FINS LIKE WATER WINDS TO PROPEL THEMSELVES THROUGH WATER, TAIL VENOMOUS, DEFENSE
VAST MAJORITY OF VERTEBRATES BELONG TO CLADE
CALLED OSTEISCHTYES
NEARLY ALL OSTERICHTHYANS HACE AN
OSSIFIED BONY ENDOSKELETON WITH A HARD MATRIX OF CALCIUM PHOSPHATE`
AQUATIC OSTERICTHYANS
FISH!`
how do most fish breath?
drawing weater over four or five paris of gills located in chambers covered by a protective bony flap called the operculum
water is drawn into the
mouth, pharyth, out between gills by movement of operculum and contraction of muscles surrounding the gill chambers
most fish control their bouyancy with an
air sac known as a swim bladder
what increases bouyancy
movement of gasses from the blood to the swim bladder, making animals rise,
reansfer of gas back to the blood causes anumal to
sink
in nearly all fishes skin is
covered by flattened bony scales
glands in the skin secrete
slim mucus over the skin- reduces drag during swimming
fishes have a
lateral line system, row of tiny pits of the skin on either sides of the body
fish reprodction varies
most are oviparious, external; however others are internal fert
nearly all the aquatic osteichthyans are
ray-finned fishes- bony rays that support their fins
Ray-finned fishes serve as
a major source of protein for humans
changing water flow patterns can
hamper fish's abilit to obtain food and interferes with migratoty pathways and spawning grounds
Lobe-fins derived character
presence of rod shaped bones surrounded by a thick layer of muscle in the pectoral and pelvic fins
During devonian period
lobe fins lived in brackish water, use lobed fins to swim and "walk" under water
by the end of devonian period, lobe fin diversity dwindles and only three lineages survive
coelacanths, lungishes, tetrapods
corlacanths
thought to be extint 75 mill years ago but found south afirca
lungishes
six species in southern hemispherer, fresh water, gulp air into lungs, gills, ponds shrink in dry season, burrow into the mud
tetrapods
limbs and feet, includes humans
fins of some lobe fins evoleved into
limbs and feet of tetrapods
tetrapods (four feet) :
in place of pectoral and pelvic fins, limbs with digits
limbs support a tetrapods weight on land, while feet with digits...
transmit muscle generated forces to the ground when it walks
what brough chasnges to tretrapod body plan
life on land
head is
separated from body by a neck
tetrapod body plan did not evolve how..
out of nowhere but was simply a modification of a preexisting body plan
most early tetrapods remained tied to water, a characteristic they share with
tetrapods called amphibians
slamanders are
order Urodela, tailed ones
frogs
order anura, tail-less ones
caecilians
order apoda, legless ones
salamandars
paedomorphosis, when mature retains larval features
anuras are more
specialized than urodela for moving on land
adopans
caecilaisna are legless and nearly blind, look like earthworms
amphibians mean
both ways of life , life stages of many frog species that live first on water and then on land, tadpole-metamorphosis, second life
amphibians do not have a
dual aquatic and terrestial life
what kind of habitats are most amphibians found in
damp
moist skin aids in
gas exchange with the environment, some lack lungs and breath through their skin and oral cavity
fertilization is what in most vertebrates
external: male graps the femal and spills his sperm ove rtthe eggs as the female shed them
ampibians typically lay their eggs in
water or moist environmetns- eggs lack a shell dehydrate quickly in dry air, eggmortality is high
many differnet egg things
some carry on back, stomach, ect
vocalizing
breeding territories to attract new mwmbers, femalses
there has been an alarming decline in amphibian pop
habitat loss, climate change, pollution, osme led to extinction
amniotes are
tetrapods that have a terrestrialy adapted egg
what are the extant members of the amniotes?
reptiles and mammals
what are amniotes named for?
amniotic egg
four specialized membranes of the amniotic egg:
1) amnion 2) chorion 3)yolk sac 4)allantois
extraembryonic membranes
they are not part of the embryo itself and develop from tissue layers that grow out from the embryo
the amnion
encloses a compartment of fluid that bathes the embryo and acts as a hydraulic shock absorber
what do the other membranes in the egg function with?
gas exchange, the transfer of stored nutrients of the embryo, and waste storage
what did the amniotic egg allow the embryo to do?
develop on land in its own private pond, reducing the dependence of tetrapods on an aqueous environment for reproduction.
amniotic eggs of most reptiles and some mammals have a
shell
the shells of birds eggs are
calcareous (made of calcium carbonate) and inflexible
shells of many other reptiles are
leathery and flexible
what does either kind of shell slow
dehydration in air - helps amniotes occupy a wide ranfe of terrestrial habitats than amphibians, their closest living relatives
most mammals have dispensed with the eggshell, and how does the embryo avoid dessication
developing within the amnion inside the mother's body
life on land adaptation of amniiotes
rib cage to ventilate lungs
what may have allowed amniotes to abandon breathing through their skin and develop less permeable skin thereby conserving water
increased efficiency of rib cage ventilation
amniote fossils have not been found early because
they are so delicate
where did the earliest amniotes live?
warm, moist environments, but they expanded to new dry and high lattitude regions
earliest amniotes were
small and had sharp teeth- predators, then later they had grinding teeth (herbivores)
earliest reptiles resembled
lizards
derived characters that distinguish reptiles from other tetrapods
reptile have scales of the protein keratin (help protect skin from abrasion and dessication); most reptiles lay their shells on land, internal fertilization (before egg shell is secreted)
snakes and lizards aew
viviparous
reptiles are mistakenly called
cold blooded
reptiles are actually
ectothermic- they absorb external heat as their main source of body heat
how can an ectothermic reptile survive on less than ten percent of food energy required by a mammal of the same size
by warming themselves directly with solar energy rather than through the metabolic breakdown of food
the entire reptile clade is ectothermic
false
birds are
endothermic- capable of maintaining body temperature through metabolic activity
parareptiles
large stocky quadrupedal herbivores, some have plates on their skin- defense against predators
diapsids
pair of holes on each side of skull, muscles attach to the jaw through these holes and conteol jaw movement
two main lineages of diapsids
lepidosaurs (tuataras, lizards, snakes, marine reptiles); archosaurs (crocodillians, pterosaurs, dinosaurs)
pterosaurs
originated in the late triassic, first tetrapods to exhibit flapping flight, pterosaur wing was completely different from the wings of bird or bats- collagent stenthened mebrane that stretched between trunk or hind leg anf a very long digit on the foreleg, they could adjust their membranes to assist in flight
dinosaurs
ornighischians-herbivores (defense against predators, tail clubs horned crests); saurischians-long necked giants; theropods- bipedal carnivores (T-Rex)
debate against dinosaur metabolism
hot mesozoic climate, adaptations such as basking, ectotherms;some dinosaurs were endotherms- gave rise to birds (all birds are endothermic)
dinosaurs were traditionally described as slow, sluggish, now..
they are described as agile, fast moving, limb structure enabled them to walk more efficiently, traveled in groups, some built nests as birds do today
all dinosaurs except birds became extinct during which period
Cretaceous period, asteriod
lepidosaurs
two species of lizard like reptiles called tuatara
new zealand, rats that accompanied humands devoured tuatara on main islands
only few remain, feed on bird eggs, insencts, small chicks
other living lineage of lepidosaurs
lizards, snakes, (squamates)
what is the most numerous and diverse group of reptiles?
lizards
legless lepidosaurs
snakes
who did snakes descend from
lizards with legs
how are snkaes proficient in moving without legs?
producing waves of lateral bending that pass from head to tail, force exerted by the bends against solid objects pushes snake forward. snakes can move by grippibg ground with their belly scales at several points of body
snakes are
carniverous
adaptations of hunting prey for snakes
acute chemical sensors, lack eardrums yet sensitive to ground vibrations- detect movement of prey, heat detecting organs sensitive to minute temperature changes, venomous snakes inject toxins through sharp teeth, toungue not venomous but helps fan odors toward olfactory organs on roof of mouth, loosly articulated jaw bone and elastic skin enable most snakes to swallow prey much larger than its head
what is the most distinctive group of reptiles alive today?
turtles
anatomy of turtle
box like shell made of upper and lower sheilds that are fused into vertebrae (clavicles) and ribs, hard shell-defense against predators
fossils indicate what about turtle shells
turtles aquired full shells in stages
side necked turles fold their neck
horizontally
vertical necked turtles fold their neck
vertically
some turtles have adapted to__, but most live in
deserts; ponds and rivers. others returned to the sea
sea turtles have
reduced shell and enlarged forelimbs that function as flippers, include the largest living turtles-deep diving leather backs
earliest crocodillians were
small terrestrial quadrupeds with long, slender legs.
later crocodillians became
larger and adapted to aquatic habitats, breathing air through upturned nostrils, may have attacked dinosaurs at water's edge
where do these live
warm regions of the globe. alligators in the southeaster US used to be endangered
what do birds and crocodilliand have in common and differ?
they are both archosaurs, but birds are mainly adapted to flight
derived characters of birds
mainly for efficient flight: weight saving modifications-lack urinary bladder, one ovary, small gonads, toothless..
wings and feathers- B keratin, shape and arrangement-airfoils
power of flapping wings comes from
contraction of larger pectoral breats muscles anchored to a keel on the sternum
some birds have what in terms of wings
wings apapted to soaring and only flap occasionally, others must flap continuously to stay aloft -swifts fastests
benefits of flight
enhances hunting and scavaging- consuming insects; ready escape from predators, migrate great distances, exploit food sources, breeding
what requires a great expenditure of energy from an active metabolism
flying; bired are endothermic, some feathers and layerof fat provite insulation for birds to retain body heat
what supports a high rate of metabolism for birds?
efficient respiratory system and a circulatory system with a four chambered heart that keep tissues well supplied with oxygen and nutrients
acute vision and fine muscle control contribute to
flight, color vision, brain is larger than most amphibians and vertebrates
fertilization of birds
courtship rituals, internal fertilization because eggs have shells by the time they are laid
copulation of birds involves
contact between mate's vents the opening to their cloacas
birds belong to the group of bipedal saurischian dinosaurs called
theropods
how did flight evolve in theropods?
chasing prey, escaping predators- extra lift; flapping feathered forelimbs, gliding
flightless species of birds
ratites ( ostrich, rhea, kiwi, cassoway ,emu)
in ratites, order Struthioniformes
sternal keel is absent, and the pectoral muscles are small relative to those of birds that can fly
penguins make up the flightless order
spenisciformes- have powerful pectoral muscles used to "fly" in wter, rails ducks some pigeons
bird beak shape suited to different
diets, some have crushing breaks to crack open hard nuts and seeds, filter feeders- beaks have stainers that enable them to capture food particles from the water
foot structure in birds is also varied
perching on branches, grasping food, defense, swimming or walking, courtship
mammals are
amniotes that have hair and produce milk
distinctive character in which mammals get their name
mammary glands, which produce milk for offspring
what do all mammalian mothers do?
nourish their young with milk, rich in fat, sugar, protein, minerals, vitamines
what retains heat in mammals?
hair and a fat layer under the skin
mammals are __ like birds and have
endothermic; high metabolic rate
what supports a mammal's metabolism
efficient respiratory and circulatory systems (4 chambered heart) diaphragm helps ventilate the lungs
mammals have a larger __ compared to other vertebrates of equivalent size?
brain
what extends mammalian offspring to learn important survival skills
relatively long duration of parental care
what kind of teeth do mammalian have
differentiated teeth- variety of teeth with different sizes - shapes adopted for chewing many types of food.
humans have teeth modified for
shearing (insisors, canines) and for crushing and grinding (premolars and molars)
mammals belong to a group of amniotes called
synapsids
early nonmammalian synapsids lacked
hair, had a spwling gait and laid eggs
what is a distinctive characteristic of synapsids
single temporal fenestra- hole behind the eye socket on each side of the skull
how do humans retain this feature?
your jaw muscles pass through the temporal fenestral and anchor your temple; two of the bones that made up jaw joint were incorporated into the mammalian middle ear
how is evolutionary change reflected
changes that occur in development. mammalian embryo grows, posterior region of its jaw can be observed to detach from the jaw and migrate to the ear, where it forms the malleus
synapsids evolved into
large herbivores and carnivores during the Permian period
by the early Cretaceous, three major lineages of mammals had emerged:
monotremes (egg laying mammals), marsupials (animals with a pouch), eutherians (placental mammals)
what gave rise to large predators and herbivores as well as flying aquatic species in the late Cretaceous period
mammals underwent adaptive radiation
monotremes are found in __ and are represented by __
Austrailia and New Guinea; one species of platypus and four species of echidnas
characteristics of montremes
lay eggs, have hair and produce milk but lack nipples. milk is secreted by glands on the belly of the mother. after hatching baby sucks the milk from the mother's fur
what are examples of marsupials?
oppossums, kangaroos, and koalas
both marsupials and eutherians share
derived characters not found in among monotremes: higher metabolicc rates, nipples, give birth to live young, embryo develops inside the uterus and the extraembryonic membranes that arise from the embryo form a placenta-nutrients diffuse into the embryo from the mother's blood
characteristics of marsupials
born very early in its development and completes its embryonic development while nursing, nursing young are held within a maternal pouch called a marsupium
where are marsupials found today
austrailian region and in north and south america
what has led to diversity of marsupials that resemble eutherians
convergent evolution in austrailia
what are eutherians commonly called and why?
placental mammals because their placentas are more complex than those of marsupials
characteristics of eutherians
eutherians have a longer pregnancy than marsupials. young wutherians complete their embryonic development within the uterus, joined to their mother by a a placenta
what does a eutherian placenta provide
an intimate, long lasting association between the mother and her developing young
what does the mammalian order of primates include?
lemurs, tarsiers, monkeys and apes (humans)
most primates have
hands and feet adapted for grasping and their digits have flat nails instead of claws like other mammals, skin ridges on fingers, large brain, short jaws-flat face, parnetal care, complex social behavior
the earlist known primates were
tree dwellers, so adaptations had to do with living in the trees
grasping hands and feet allow primates to
hang onto tree branches
all primates have
big toe that is widely separates from the other toes to grasp branches with their feet, thumb thatis relatively moveable and separaate from other fingers
monkeys and apes have
opposable thumb- they can touch the ventral surface (finger print side) of the tip of all four fingers with the ventral surface of the thumb in thte same hand
thumb
power grip, precise maiupulation
what represents decent with modification from our tree dwelling ancestors
unique dexterity of humans
three main groups of living primates
lemurs of madagascar, lorises and bush babies of tropical africa and southern asia, anthropods-monkeyd apes
monkeys do not form a clade but
two groups called the new and old world monkeys
all species of new world monkeys are
arboreal
old world monkeys include
ground dwelling as well as arboreal species
ape group includes the genera
hylobates (gibbons), Pongo (orangutans), Gorilla (gorillas), Pan (chimpanees and bonobons) and Homo (humans)
apes derived from __ and are now found
Old world monkeys, tropical regions of the old world except for gibbons
only blank and blank are primarily arboreal
gibbons and orangutans
compared to other primates, apes have a larger
brain in proportion to their body
humans are
mammals that have a large brain and bipedal locomotion
what is our species?
homo sapiens, 200,000 years old
what characters distinguish humans from other apes?
humans stand upright and are bipedal (walk on two legs), humans have a much larger brain and are capable of language, symbolic thought, artistic expression, and the manufacture and use of complex tools.. reduced jaw bones and jaw muscles, along with a shorter digestive tract
humans and chimpanzees genomes are
99 percent identical, hoerver a difference of 1 percent can translate into a number of changes in a genome that contains three buillion base pairs
how manby genes to humans and chimpanzees differ in?
19 regulatory genes
such genomic differences seperate humans from what kinds of apes
living apes. but many of these new characters emerged in our ancestors long before we appeared
paleoanthropology
the study of human origins
hominins
species that are more closley related to humans than to chimpanzees
oldest hominin
sahelanthropus tchadensis
early hominins had
reduced canine teeth, relatively flat faces, upright and bpedal than other apes, --foramen magnum: hole at the base of the skull through which the spinal cord exists-- in chimps, far back, in humans and homins, underneaththe skull-- hold our head directly over our body
hominins from 2-4 million years ago, when diversity increased
australopiths: paraphyletic
early homo
H.habilis, homo ergaster
who marks an important shift in relative sizes of the sexes?
Homo ergaster
when was sexual dimorphism significantly reduced
early homo
what does extreme sexual dimorphism associated with
male-male competition for multipple females
homo neanderthalensis (neanderthals)
thick boned hominin with a prominent brow, Europe, had a brain the size as a human, tools
what did the palenthings consider neanderthals
stage in evolution of homo eructus into homo sapiens
why was this view abandoned
analysis of mitochondiral DNA; limited gene flow between the two species
ancestors of humans originated in
africa
what do studies of the Y chromosome suggest
humans spread beyong africa in one or more waves, first into Asia and then to Wurope and Austrailia
physiology
biological function
body plan of an animal
result of a pattern of development programmed by the genome, itself the product of millions of years of evolution
physical laws do what?
govern strength, diffusion, movement, and heat exchange which limit the range of animal forms
fusiform
tapered on both ends
what is an example of convergent evolution
similar shape found in these speedy vertebrates
maximum size is also influenced by
physical laws
how so?
aas body dimensions increase, thicker skeletons are required to maintain adequate support. as bodies increase in size, the muscles required for locomotion must represent an ever larger fraction of the total body mass.
what imposes limitation of animals body plan?
exchange of materials with their environment
exchange occurs as
substances dissolved in an aqueous solution move across the plasma membrane of each cell
what are the rates of exchange for nutrients, waste ect porpotional to?
membrane surface area, whereas the amount of material that must be exchanged to sustain life is proportional to cell volume
what does the opportunity for exchange depend on?
number of cells in an organism's body
an animal is composed of many cells, so
each having a plasma membrane in which exchange must occur. therefore a multicellular organization therefore works only if every cell has access to a suitable aqueous environment, either inside or outside the animal's npdy
a common body plan that maximizes exposure to surrounding medium is
a flat shape
the bodies of most animals are somposed of
compact masses of cells, complex
what does increasing the number of cells do?
decreases the ratio of outer surface area to total volume
what links exchange surfaces to body cells?
internal body fluid
what are the spaces between cells filled with?
interstitial fluid
exchange between the interstitial fluid and the circulatory fluid encals cells throughout the body to
obtain nutrients and get rid of wastes
benefits of complex body plans over simple ones
an external skeleton can protect against predators, and sensory organs can provide detailed information on the animal's surroundings, digestion gradually-controlling stored energy release, can maintain relatively stable internal environment while living in a changeable external environemtent
heirarchal organization of Body Plans
cells-tissues-organs-organ systems
sometimes organs have different roles that can
make them part of two different system; ex pancreas produces enzymes that ate critical for digestive sustem but also regulates sugar levels for the endocrine system
bottom up (cells to organ systems) reveals
emergent properties
top down reveals
multilayered basis of specialization
four main types of animal tissues
epithelial, connective, muscle and nervous
coordinating activity across an animals body requires
communication between different locations of the body
in the endocrine system, signaling molecules released into the body by endocrine cells...
reach all locations in the body
in the nervous system, neurons transmit..
signals called nerve impulses between SPECIFIC locations in the body
hormones
the signaling molecules broadcast throughout the body by the endocrine system
only cells that have what respond to a hormone
receptors for a particular hormone
hormones
the signaling molecules that are broadcsted throughout the body
hormones are relatively
slow acting
in the nervous system, signals are not
broadcasts throughout the whole body, instead each nerve impulse travels to specific target cells along dedicated communication lines consisting of mainly axons
communication in the nervous system usually involves
more than one type of signal, travel in long distances along axons as changes in voltafe, very short range chemical signals, transmission is extremely fast
the endocrine system is well suited for
coordinating gradual changes that affect the entire body, such as growth and development, reproduction, metabolic processes and digestion
the nervous system is well suited for
directing immadiate and rapid responses to the environemnt, especially in controlling fast locomotion and behavior
the two systems work in
close coordination
feedback control maintains
the internal environment of many animals
animals manage their internal environemnt by
regulating or conforming
regulator
uses internal mechanisms to control internal change in the face of external fluctuation
conformer
allows its internal condition to change in accordance with external changes in the variable
an animals may
regulate some internal conditions while allowing others to conform to the environemt
homeostasis
"steady state", the maintainance of internal balance. animals maintain a contstant internal environment even when the external environment chagnes significantly
what is an animals achievemtn of homeostasis similar to
home heating system
how?
maintaining a variable at or near a particular value (Set point). Fluctuation of value above or below the set point (stimulus) directed by a receptor (sensor), control center receives message from sensor, generates output that triggers a responese
drop in temp below set point
stimulsu
thermostat
control center and sensor
heater
produces response
homeostasis in animals relies largely on
negative feedback- reduces or damps the stimulus
homeostasis is a
dynamic equillibrium, the interplay between external factors that tend to change the internal environment and internal control mechanisms that oppose such changes
why does homeostasis moderate but no eliminate changes in the internal environemtn?
responses to stimuli are not instantaneous
aditional fluctuation occuts if
a variable has a normal trange- upper and lower limit- rather than a single set point
homeostasis is enhanced by
adaptations that reduce fluctuation, such as insulation in the case of temperature and physiological buffers in the case of pH
positive feedback
a control mechanism that amplifies rather thatn reduces stimulus- helps drive processes to completion
set points and normal ranges for homeostasis can
change under various curcumstancs, regulated changes are essential to birnak body function
circadian rhythm
a set of physiologucal changes that occur roughly every 24 hours
example of circadian rhythm
body temperatur undergoes a cyclic rise and fall of temor, biological clock can maintain this rhthym even with variations in human activty, ect.
what is one way in which the normal range of homeostasis may change
acclimatization- the gradual prosess by which an animal adjusts to changes in its external environment
homeostatic processes for thermoregulation involve
form, function and behavior
thermoregulation
process by which animals maintain an internal temperature within a tolerable range
why is thermoregulation critical to survival
most biochemical and physiological processes are very sensistive to chagnes in temperature
increases in temperature
speed up reactions, but cause some proteins to become less active
each animal species has
an optimal temperature reange, thermoregulation helps maintain body tempereature within that optimal ranfe-cells to function effectively even as the external environemnt fluctuates
what are the sources of heat for thermoregulation
internal metabolosims and external environemnt
endothermy and ectothermy are not
mutualy exclusive modes of thermoregulation
ectotherms generally need to consume
much less food than endotherms of equal size- an advantage if food supply is limited
ectotherms usually tolerate
larger fluctuations in internal temperature
behavior means to adjust temperature
shade, basking in the sun
animals can either have what or what body temperature?
variable or constant
poikolotherm
an animal whose body temperature varies with the environment
homeotherm
has a relatively constant body temperature
in endotherms there is no fixed relationship between
the source of heat an the stability of body temperature
thermoregulation depends on
an animals abbility to control the exchange of heat with its environment
organisms exchange heat by four processes
radiation, evaporation, convection, and conduction
heat is always transferred from
an object of higher temperature to one of lower temperature
integumentary system
the outer covering of the body, consisting of the skin, hair and nails
insulation
reduces flow of heat between an animal and its environment.
sources of insulation include
hair, feathures, layers of fat from adipose tissue
insulation example
raising fur or feathures traps a thikcer layer of air, increasin insularion power. secrete oily substance, goosbumps-vestige of hari raising inherited by furry ancestors
circulatory systems provide a major route for
heat flow between the interior and exterior of the body
animals do what in response to change in temperature
alter the amounf of blood (heat) flowing between their body core and their skin.
nerce signals that relax the muscles of the bessel walls resulst in
vasodilation- the widening og superfivcial blood vessels ( those near body surface)
as a consequence of increase in vessel diameter,
blood flow in the skin increases
vasoconstriction
reduces blood flow and heat transfer by decreasing the diameter of superficial vessels
reducing heat loss from the body relies on
countercurrent exchange- the transfer of heat between fluids that are flowing in opposite directions, arteries and veins located adjacent to eachother
because blod flowa through thareteries and the veins in oppposite directions,
heat is transferred along the entire length of the exchanges, maximizing the rate of heat exchange
countercurrent heat exchange is founf in
large, powerful swimmers
what enables the vigourous activity of these animals
keeping main swimming muscles several degrees warmer than tissues near the surface
what is the only way to keep body temperature from rising
evaporation
how do terrestrial animals lose water
evapotarion from their skin and respiratory surfaces
what are two behavioral adaptations in resoinse to tempe
hibernation or migration
all amphibians and reptiels (ectothermicO mainly control body temperture by
behavior
postures and directions
maximizes or minimizes absorption of heat from the sun
social behavior example
honey bees huddling together
why must endotherms counteract continual heat loss
they maintain body temp considerably higher than that of the environment
how can endotherms vary heat production to match changing rates of heat loss
thermogenesis (muscles acticvity, shivering)
in some animals, certiaain hormones can cause
mitochondira to tincrease their metabolic activtyi and produce heat instead of ATP- noshivering thermogensis (brown fat) rapid heat priduction
many species of insescts bees moths are
enodthermic, powerful flight muscles generate heat when contracting
what often includes adjusting insulation
acclimitization to seasonal temperature changes (growing a thicker coat in winter)
acclimization of ectotherms incluse
adjustments at the cellular level, enzymes with same function, different optimal temperature, porpotion of sat/unsat lipids in membranes chagne, antifreeze
the sensors for thermoregulation are concentrated in a a breain region called the
hypothalamus
what functions as a thermostat
nerve cells in hypothalams, responding to body temperature outside a normal range by activating mechanisms that promote hat loss
warm receptors signal the hypothalamic thermostat when,
temperatures increas, cold when temperatures decrease
what happens at body temperatures below the normal range
thermostat inhibits heat loss mechanisms and activates heat-saving ones, such as vasoconstriction, raisong of fur, stimulating heat gen mechs (shivering and nonshivering thermo)
fever
elevated body temperature
fever reflects
an increase in the set point for the biological thermostat.
bioenergetics
the overflow and transformation of energy in an animal
what determines nutritional needs and is related to the animal's size, activity and environmemt?
bioenergetics
organisms can be classified according to
how they obtain chemical energy
autotrophs
use light energy to build energy riich organic molecules and rhen use those organic molecules for fuel
heterotrophs
must obtain their chemical energy from food, which contains organic molecules synthesized by other organisms
how is food digested
enzymatic hydrolysis
how are nutrients absorbed
by body cells
most nutrient molecules are used to
generate ATP, ATP produced by cellular respiration and fermentation powers cellular work, enabling cells, organs and organ systems to perform the functions that keep an animal alive.
energy in the form of ATP is also used in
biosynthesis- needed for body growth and repar, sysnth of stoage material such as fat, production of gametes
the prodcution of ATP gives off
heat, which the animal eventually gives off to its surroundings
metabolic rate
the amount of energy an animal use in a unit of time; the sum of all energy used in biochemical reactions over a given time interval
why is metabolic rate mesured by monitoring an animal's rate of heat loss?
nearly all of the energy used in cellular respiration eventually appears as heat, calorimeter-animal's heat loss
metabolic rate can also be determined by
CO2 produced or O2 consumed by an animal's cellular respiration
basal metabolic rate
the minimum metabolic rate of a non-growing endotherm that is ar rest, has an empty stomach and is not experiencing stress
BMR is measured under
a comfortable temperature range
the minimum metabolic rate of ectotherms is determined at a specific temperature becase
changes in the environmental temperature alter body temperature and therefore metabolic rate
standard metabolic rate
the metabolic rate of a fasting,nonstressed ectotherm at rest ar a particular temperature
what reveals that endo and ectothermy have different energy costs?
comparisons of minimum metabolic rates
metabolic rate is affected by
age, sex,size, activity, temperature, nutrition
larger animals hsve more body mass and therefore
require more chemical energy
the energy it takes to maintain each gram of body mass is
inversely related to body size
as bosy size becomes smaller,
eaxh gram of tissue increases in energy cost
as body size increases
energy cost per gram of tissue decrease but an ever larger fraction of body tissue is required for exchange , support and locomotion
maximum metabolic rates occue durin
peak activity
max met rate can sustain is
inversely related tothe duration of the activity
torpor
a physiological state of decreases actuvuty ans metabolism
adaptation that enables animals to save energy while avoiding difficult and dangerous condition
torpor
hibernation
long term torpor, adaptation to winter food scarcity
when a mammal enters hibernation
its body temperature declines as its body temperature is turned down
every two weeks or so
an animal gets aroused to produce heatr
estivation
summer torpor, enables animals to survive long periods of high temp and scarce water
circadium rhythm in hibernating animals
the clock stocks operation during hibernation
nutrition
food being taken in, taken apart, and taken up
herbivores
dine mainly on plants or algae
carnivores
mostly eat other animals
omnimores
regularly consume plants or animals
an adquate diet must satisfy three nutritional needs
chemical energy for cellular processes, organic building blocks for macromolecules and essential nutrients
how do animals meet the continuous requiremtn for ATP?
injest and digest nutrients, carbs protiens lipds, for use in cellular respiration and energy storage
an animal diet must supply
raw materials needed for biosynthesis
an animal must obtab two types of organic precursors from its food for
buiding complex molecules it needs to grow, maintain itself and reproduce
what are the two
siurce of organic carbon (sugAR) and a soucr of organic nitrogen (protein)
essential nutrients
the material that an animals' cell require but cannot synthesize
four classes of essential nutrients
essential Amino acids, essential fatty acids, vitamines and minerals
animals require what to make protein
20 amino acids
as long as their diet contains ___ animals have enzymes to snthesize half of these AA's
sulfur and organic nitrogen
the remaininf acids (essential) must be
obtained from food
most animals, adult humans require how many AA's in their diet
8
complete proteins
provide all the essential amino acids in their proper amounts
incomplete
being dificient in one or more essential amino aicds
some animals have
adaptations that help them throuigh periods when their bodies demand extraordinary amounts of protein
essential fatty acids
are certain fatty acids that contain one or more double bonds and are thus unsaturated
vitamins
organic molecules that have diverse functions and are required in the diet in very small amounts
how many vitamins have been identified in humans?
13
how are vitamins classified
water or fat soluble
water soluble vitamins inclus
the B vitamines- compounds that function as coenzymes, and vitamin C- required for production of connective tissue
fat soluble vitamins
vitamin A- visual pigments of the Eye, vitamin K-blood clotthing vitamin D- calcium, bone, sunlight
overdoses of water soluble vitamines are
harmless - excess of these vitamins are excreted in the uroine
excess fat soluble vitamins is
harmful, deposited in body feet, so iversonsumption may result in accumulating toxic levels of these compounds
mineral
inorganic nutrients, usually required in small amounts such as iron and sulfur, enzyme structure
what results in malnutrition?
a diet that lacks one or more essential nutrients or consistently supplies less chemical energy than the body requires- failure to obtain adequate nutrition
insufficient tintake of essential nutrients can cause
deformities, disease, even death
most common type of diffieciency in humans
protein difficiency
vitamin A difficiency
simple rice diets, can lead to blindness or death- beta-carrotene is converted to vitamin A "Golden rice"
what resulted in undernutrition?
a diet that fails to provide adequate sources of chemical energy
what happens when animal is undernourished
body uses up stored carbs and fat and then begins breaking down its own proteins for fuel, muscles decrease in size, brain becomes protein difficient
food processing can be divided into four distinct stages:
ingestion, digestion, absorption and elimination
ingestion
the act of eating or feeding
digestion
food is broken down into molecuels small enough for the body to absorb
mechanical digestion
typically process chemical digestions (chewing)
what does mechanical digestion do
breaks food into smaller peices, increasinf the surface area available for chemical processes
chemical digestion is necessary why
because animals cannot directly use the proteins, carbs, nucleic acids, fats and phospholipds in food
some molecules are too large to pass through membranes that enter cells of animsl, . large meolecules are broken down into their componets, however
animal can use these smaller molecules to assemble the large molecules it needs
chemical digestion by enzymes reverses process how
breaking bonds with the addition of water- enzymatic hydrolysis
a variety of enzymes catalyze digestion of large molecules into food:
polysaccharides and dissacharides are split into simple sugars; proteins are broken fown into amino acids and nucleic acids are cleaved into nucleotides and their componets
enzymatic hydrolysis also
releases fatty acids and other componets from fats and phospholipids
absorption
animals cells take up small molecules such as AA's and simple sugars
elimination
completes the process as undigested material passes out the digestive system
what is the adaptation found across a wide ranfe of animal species
processing of food within specialized compartments
such compartments can be:
intracellular- in the form of food vacuoles or extracellular- digestive organs or systems
food vacuoles
cellular organellesinwhich hydrolytic enzymes break down food
what are the simplest digestive compartment
food vacuoles
intracellular digeston
hydrolysis of food inside vacuoles
when does this begin?
after a cell engulfs solid food by phagocytosis or liquid food by pinocytosis
newly formed food vacuoles do what
fuse with lysosomes, organelles containing hydrolytic enzymes- brings food in containcr with the enzymes- allowing digestion to occur safely within a compartment encoles by protective membrane
extracellular digestion
breakdown of food incompartments that are continuous with the outsifde of the animal's body
what enables an animal to devour much larger peices of food that can be ingested by phagocytosis
having one or more extracellular compartments for digestion
simple body plans have a digestive compartment with
one opening- gastrovascular cavity- digestion/dist. nutrietns across the body
most animals have a digestive tube extending between
two openings, a mouth and an anus
what is the tube called
complete digestive tract or alimentary canal
the tube can be organized into specialized compartments that carry out digestion and nutrient absorption in a stepwise fashion why
because food moves along canal in single direction
an animal eith an alimentary canal can
ingest food while earlier meals are still being digested
what forms the mammalian digestive system?
organs specialized for sequential stages of food processing
in mammals digestive system consists of
alimentary canal and the various accessory glands that secrete digestive juices through ducts into the canal
what are the accesory glands of the mammalian digestive system?
three pairs of salivary glands, pancreas, live and gal bladder
peristalsis
alternating waves of contraction and relaxation in the smooth muscles lining the canal
how is food pushed along alimentary canal
peristalsis
at some of the junctions between specialized compartmets, the muscles layer forms
ringlike valves called sphincters
sphincters regulate
passage of material between compartments
ingestion and the initial steps of digestion occur where
the mouth, or oral cavity
mechanical digetion,
cut mash grind food- easier to swallow
presence of food stimulates
NERVOUS REFLEX THAT CAUSES SALIVARY GLANDS TO DELIVER SALIVA THROUGH DUCTS TO THE ORAL CAVITY
saliva initiate what while doing whta
chemical digestion while protecting the oral cavity
the enzyme amylase found in saliva does what
hydrolyzes starch (glucose polymer from plants) and glycogen (animals) into smaller polysaccharides and the disacharide maltose
what is a viscous mixture of water, salts, cells and slippery glycoproeins called mucins that causes the protective effect of saliva
mucus
what about mucus/
protects lining of mouth from abrasion and lubricates food for easier swallowing
how does toungue aid digestive processes
evaluating ingested material and then enabling its further passage: distinguishing what foodsshould be process further. after food is deemed acceptable chewinf commences
toungue movements manifulate the food, heloing
it shape into a ball- bolus
what does the toungue do during swallowing?
pushes bolus to the back of the oral cavity and into the pharynx
pharynx (throat region) opens to two passage ways
the esophogas and the trachea
esophogus connects ot
stomach
trachea leads to
lungs
swallowing must be carefully choreographed
to keep food from entering and blocking air way
what happens when you swallow
a flap of catilage called the epiglottis covers the glottis (vocal cords and openings between them)
what directs each bolus into the entrance intp the esophagus
the swallowing reflex
esophogus contains both
striated and smooth muscle
striated muscle
sityated at the top of the esophogus and is active during swallowing
smooth muscle functions
in peristalsis through the rest of the esophogus
where is the stomach located and what does it do
just below the diaphragm, stores food and begins digestion of PROTEINS
the stomach secretes a digestive fluid called ___ and mixes this with the food through __
gastric juice; churning action
what is this mixture called
chyme
two componets of gastric juice carry out chemical digestion:
HCl- disrupts the extracellular matrix that binds c ells together in meat and in plant material
low pH of HCl does what
denatures proteins in food, increasing exposure to peptide bonds
the exposed bonds are attacked by the
protease, protein digesting enzyme- pepsin
pepsin works best in what environment and deos what
acidic, breaks peptide bonds- cleaves proteis into smaller polypeptides
where does further digestion to indv aa's occur?
small intestin
why does gastric juice destroy stomach cells that make it
ingedients of gatric juice are kept inactive until they are released tothe lumen (cavity) of the stomach
parietal cells secrete
hydrogen and chloride ions, which form HCl
cheif cels release pepsin into the lumen in an inactive form called
pepsinogen
HCl converts pepsinogen to active pepsin by
clipping off a small portion of the molecule and exposing its active site
how is chemical digestion by gastric juice facilitates?
by the churning action in the stomach
acid reflux
a backflow of chyme from the stomach into the lower end of the esophogus resluting of irriattion of the esophogas- heart burn
what helps regulate passafae into the smalle intestine and how
the sphincter located where the stomach opesn tothe small intestine by allowing only one squirt of chyme at a time
most enzymatic hydrolusus of the macromolecules from food occurs where
the small intestine
what is the alimentary canal's longest compartment
small intestine
the first 25 cm/10 in forms the
duodenum
hormones released by the stomach and duodenum control
digestive secretions into the alimentary canal
how does the pancreas aid chemical digestion
producing an alkaline solution rich in bicarbonate as well as several enzymes - neutralizes acidity of chyme and acts as a buffer
digestion of fats and other lipids begins in the and relies on
small intestin, producion of bile- mixture of substances made in the liver
bile contains
bile salts, emulsifiers (detergents) aid in digetion absorpton of lipids
where is bile stored and concentrated in the
gall bladder
what is the source of many digestive enzymes
epithelial lineing of the duodenum
most digestion is completed in the
duodenum
what functions mainly in the absorption of nutrients and water?
jejunum and ileum
nutrients in the lumen must first cross __ to reach body tissues
the lining of the alimentary canal
large linings encircles the intestine and are studded with
finger-like projections called villi
each epithelial cell of a villus has on its apical surface
many microscopic projections or microvili that are exposed to intestinal lumen
transport across epithelial cells can be
passive or active
active tranport allows
much more absorption of nutrients than would be possible with passive diffusion allone
where do the capillaries and veins that carry nutrient rich blood away from the villi all converge into
the hepatic portal vein- a blood vessel that leads directly to the liver
this arrangemtn serves to major functions:
allows liver to regulate distribution of nutrients to the rest of body, arrangemtn allows liver toremove toxic substances before the blood circulates broadly