Animal Biology Test 4

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Deuterostomes
blastopore becomes the anus, anus forms first, regulative cleavage
After the first sets of divisions blastomeres set up gradients of morphogens across the embryo that define cell identity
How is cell fate primarily determined in deuterostomes?
Superphylum
Which one of the following taxonomic ranks is the most inclusive?
Ambulacra
feeding groves
Phylum Echinodermata
prickly skin, pentaradial symmetry(adult), water vascular system, dermal branchiae, pedicellariae, endoskeleton, nerve net, cannot osmoregulate, few predators
Water vascular system
coelom compartment modified for hydraulic movement
Dermal branchiae
thin extensions of body cavity that function as gills
Pedicellariae
claws on outersurface for cleaning and defense
Class Asteroidea
seastars, adults lack anterior or posterior end, body has oral and aboral sides, central disc with arms (multiples of 5), madreporite, ambulacral groove lined with tube feet runs along the oral surface of each arm
Madreporite
opening to water vascular system
Water vascular system
only in enchinoderms, coelomic compartment (filled with seawater) used as a hydraulic system, terminates in tube feet
Ossicles
calcareous plates
Catch collagen
connects ossicles, alternates between stiff and fluid states, controlled by nervous system, allows enchinoderms to "fix" shape or position without muscle effort
Echinodermata circulation
no circulatory system, cilia move fluid around water vascular system
Echinodermata excretion
no excretory system, ammonia diffuses from body through epithelia of dermal branchiae and tube feet
Echinodermata development
asteroids, bilateral larvae to radial adults, anterior-posterior axis degenerates, left side becomes oral surface, right side becomes aboral surface, new anus and mouth forms
Class Ophiuroidea
brittle and basket stars, lack pedicellariae and dermal branchiae, tube feet lack ampullae (cannot create suction), madreporite is on oral surface, arms have vertebra-like jointed ossicles, nocturnal, particle or filter-feeders
Class Echinoidea
sea urchins and sand dollars, no arms (arms and ambulacral grooves wrap around and fuse to aboral side), larva: pluteus
Revert back to bilateral symmetry
some echinoids evolutionarily reverted back, secondarilly derived anterior-posterior axis, anus relocated to oral side (both on one side), appropraite for forward movement through sediment where they live
Class Holothuroidea
sea cucumbers, elongated oral-aboral axis, secondarilly "bilateral", feed on marine snow and detritus, small ossicles provide no support, madreporite floats within coelom, lack pedicellariae, respiratory tree branches from digestive system to exchange gases and waste
characteristics of chordates
1- notochord, 2- dorsal hollow nerve cord, 3- pharyngeal pouches or slits, 4- post anal tail, 5- endostyle
notochord
dorsal, semi-rigid rod, first skeletal element to develop in chordate embryos, not present in most adult chordates, composed of cells with large vacuoles, surrounded by a sheath
Dorsal hollow nerve cord
dorsal to notochord, neural plate (dorsal, ectodermal tissue) folds to form a hollow tube, neural crest cells (predecessors of peripheral nerves) branch from the tube
Endostyle
region of the pharnyx that secretes mucus, aids food capture, concentrates iodine and secretes iodinated proteins
the thyroid gland is the vertebrate equivalent
Where is the endostyle in humans?
Grooves
ectodermal depressions
Pouches
endodermal invaginations
Slits
form when pouches and grooves meet, forming an opening in the pharyngeal wall
Subphylum urochordata
tail chordates, tunicates, salps, larvaceans, body encased by a protective tunic of cellulose, chodate features are present but lost as adults, pharyngeal basket catches food with a mucus net, pumps blood in alternating directions
Urochordata larvae
tadpole larvae, notochord tail and nerve cord degenerate during metamorphosis
Subphylum cephalochordata
lancelets, live in sandy coastal sediments, use pharyngeal slits to filter feed, closed circulatory system similar to fishes (ventral aorta pumps blood through pharyngeal bars to a dorsal aorta and on to systemic capillaries), no heart, do not perform gas exchange, muscles organized in myomeres, hepatic cecum
hepatic cecum
pocket of digestive tract with liver and pancreas-like functions such as digestive enzyme secretion and storage of glycogen
mammals possess both
Are mammals craniates or a vertebrates?
Myomeres
benefit?
Structural benefits of cranium
supportive, lightweight, jointed endoskeleton, evolved from plates of ectodermal bone
Subphylum craniata
vascularization of pharyngeal bars, musclular digestive movement instead of ciliary, specialization: liver and pancreas, chambered heart, glomerular nephrons and positive pressure filtration
Craniate nervous system
CNS: anterior nerve cord expanded into a triparite brain, neural crest develops protective brain case glands and Schwann cells, paired sense organs develop from ectodermal placodes
Lamprey larva
ammocoete larvae similar to ancestral vertebrates, filter feed by muscular pharyngeal pumping, posses all essential vertebrate features, chambered heart, tripartite brain with paired sense organs, pharyngeal bars modified for gas exchange, specialized digestive organs
Agnathan
jawless
Gnathostomes
jawed
Evidence for homology of jaws and gill arches
1. both are modified pharyngeal bars, 2. both originate from neural crest, 3. cranial nerve innervation of both is similar
Paraphyletic
Are fishes monophyletic, paraphyletic, or polyphyletic?
Class Myxini
hagfish, agnathan, invertebrate craniates, no skeletal elements surround nerve cord, saprophytic, notochord retained in adults, cartilaginous skeleton, no stomach, no larval stage
Class Petromyzontida
lamprey, agnathan, vertebrates, largely parasitic, notochord retained throughout life, lack a stomach but have a spiral valve in intestine increases surface area for absorption
Class Chrondrichthyes
cartilaginous fishes, bony ancestors so they may host lost bone, more than 95% are marine, partial notochord remains in adults, no swim bladder, blood isosmotic to seawater, unidue rectal gland to excrete excess NaCl
Sharks build up urea to be isosmotic with seawater
Blood and cells of marine species contain a lot of urea and urea denatures proteins. Why keep high concentrations of such a dangerous compound?
Trimethylamine oxide (TMAO)
chondrichthyes build this up to counteract the negative effects of urea
Clade Osteichthyes
"bony fishes", pocket of the gut (intestinal tract) forms a swim bladder or lung, endochondral bone: skeleton initially cartilaginous but replaced by bone later in life
swimbladders
gas-filled, offsets negative buoyancy of bones, fish change gas pressure in bladder at different depths, most fishes use O2 at 90% purity to inflate bladder
...
blood entering gas gland flows through a countercurrent exchanger, hemoglobin releases O2 at low pH (Bohr and Root effects), 1. gas gland produces lactic acid and CO2 which lowers the pH, 2. hemoglobin releases O2, 3. O2 partial pressure increases, 4. O2 diffuses into bladder
Class Actinopterygii
ray-finned fishes, bony "rays" support membranous fins, teleosts (most diverse clade)
Clade Teleosts
most diverse clade, light and thin scales instead of plate-like scales, symmetrical tail and flexible fins improve movement
Class Sarcopterygii
lobe-finned fishes, includes ancestors of tetrapods, fleshy fins have jointed bone structure, circulatory system separated in pulmonary (gill) and systemic circuits, swim bladder
e) all of the above
How do terrestrial environments differ from aquatic environments?
a) temp less stable
b) higher O2 conc in air
c) air less viscous and less buoyant
d) air less buoyant
e) all of the above
Class Amphibia
tetrapods, bony skeleton with 4 digits on each forelimb, un-shelled eggs surrounded by jelly coat, ectotherms, kidneys, produce urea as adults
Amphibia circulation
separate pulmonary and systemic loops powered by a 3-chambered heart (2 atria, 1 ventricle), partial septum in ventricle limits mixing of O2 and de-O2 blood, one of the pharyngeal arches becomes the pulmonary artery
Amphibia respiration
cutaneous, pulmonary, gill, pulmonary ventilation driven by forcing air (positive pressure) into lungs
d) all of the above
What benefits are there to double circulation?

a) facilitates higher systemic pressures, greater oxygen delivery rates to body tissues, and supports higher metabolism
b) may allow blood to bypass respiratory organs (lungs/gills) when not in use, sending blood where it is needed most
c) greater control over systemic and pulmonary/gill blood pressures allows blood flow to vary with needs
d) all of the above
Order Anura
"without tail", frogs and toads, very easily disrupted by human activity, herbivorous tadpole larvae, vocal adults (breeding songs), skin has mucous glands to protect from H2O loss, serous glands produce toxins, chromatophores give skin color
Order Gymnophiona (Apoda)
"naked snake", "no feet", caecilians, worm-like bodies with no limbs and many vertebrae, feed on worms and invertebrates, small scales embedded in skin
Order Urodela
"evident tail", salamanders, larvae and adults are carnivores, adults are typically terrestrial, males deposit a spermatophore that female picks up with her cloaca
Family Plethodontidae
salamanders, lack lungs, ancestors may have lost lungs while living in cold and well-oxygenated streams, extensive capillary beds, thinner epidermis than other amphibia, buccal (mouth) gas exchange
Amniotes
amniotic egg, thicker and waterproofed skin, lack gilled larvae, internal fertilization, ventilation of lungs by negative pressure
Amniotic egg
allowed animals to overcome the risk of dehydration during development, shell limits H2O loss, provides structural support, allows gas exchange, 4 extraembyronic membranes surround embryo, yolk sac, amnion, chorion, allantois
Yolk sac
nutrient storage
Chorion
surrounds entire egg, acts as a respiratory surface
Amnion
fluid filled cushion
Allantois
stores nitrogenous waste, performs gas exchange
Amphibia
Which class of vertebrates inhales air as adults cia positive pressure?
Fenestra
holes in the temporal region of the skull
Anapsids
no fenestrae, ancestral state
Synapsid
one fenestra, mammals and ancestor/sister groups
Diapsid
two fenestrae, reptiles
Turtle skull
taxonomically diapsids, reverted to anapsid morphology
Non-avian reptiles
more lung surface than amphibians, more efficient circulation tham amphibians, excretion: uric acid, shelled egg, keratinized skin (B-keratin), strong crushing or gripping jaws, enlarged cerebrum, complex behavior/sensory systems
Order Sphenodonta
tuataras
Order Squamata
95% of non-avian reptiles, flexible skull to better manipulate food, lizards and snakes, suborder sauria (lizards), suborder serpentes (snakes)
Suborder Sauria
lizards, external ears
Suborder serpentes
snakes, elongated, limbless, lack external ears, possess specialized heat and smell senses to locate prey
Snake jaw and skull
jaw not connected in front by bone (kinetic jaw), skull bones move independently, allows for ingestion of large prey
Neurotoxins
attacks nerves
Hemorrhagins
digests tissues, causes bleeding and tissue damage
Order Crocodilia
alligators and crocodiles, closer relatives to birds than other reptiles, 4 chambered heart allows separation of pulmonary and systemic circulation, two aortas branch from the heart which allows lung circulation to be bypassed during diving
Order Testudines
turtles, reibs and vertebrae and dermal bones fuse into shell, carapace- upper, plastron- lower, limb girdles reside within rib cage, lack teeth
Avian reptiles
feathers are modified scales, pneumatic skeleton (some bones are air filled), toothless beak, 4 chambered heart, unidirectional (non tidal) respiration, endothermic
bird migration
40% of bird species migrate seasonally, reproduce in northern latitude, overwinter in southern latitudes, go where sun is closest to the earth
feather structure
composed of B-keratin, complex structure of extensions and hooks that link strands together, hook-like barbules link barbs like velcro
avian skeleton
mass equal to equally sized mammals but distributed with low center of gravity, pneumatized bones in some parts of the body, spine stiffed by fusion of trunk and lumbar vertabrae
forelimbs
wings
furcula
wishbone, fused clavicles, store energy during wing beats
keeled sternum
origin of flight muscles, lots of area for muscle attachment
Pectoralis
depresses wing, originates on sternum
Supracoracoideus
elevates wing, originates on sternum, a tendon from here loops over the head of the humerus to insert on its dorsal surface
Avian reptile respiration
unidirectional, do not have alveoli, have air sacs and a lung of tubular parabronchi, lungs are rigid and do not expand/contract, air is drawn into and expelled via elastic air sacs, transfer oxygen to blood during inhalation and exhalation, air sacs store air but do not perform gas exchange
Avian excretion and ion regulation
primary waste product is uric acid and requires very little water to excrete, kidneys cannot concentrate urine well, salt glands
Salt glans
help some birds eliminate excess salt (and use a countercurrent multiplier to do so)
Class Mammalia
endothermic, mammary and sweat and sebaceous glands, hair, turbinate bones in nose, internalized amniotic egg with placental attachment (except monotremes), diaphragm, secondary palate, single lower jaw bone (dentary), 3 ossicles in middle ear, synapsid
Yes, endotherms can change their body temp
Echidnas are mammals. Is the echindna an endotherm?
Endotherm temp can be higher than outside temp
How to tell an endotherm from ectotherm
Pelycosarus
early synapsids, therapsid ancestors of mammals
Early mammals
were likely small insectivores
Trends in mammalian jaw evolution
dentary increases in size, other bones become smaller and co-opted for use in middle ear (malleus and incus)
Mammalian noses
shaped by impact of endothermy on need for water conservation, turbinate bones, as air enters warmth of respiratory system moisture evaporates from tissues, as air leaves during exhalation the moist air passes over cool membrane covering the turbinate bones and water condenses in the nose
Mammal skin
dead epithelial cells packed with a-keratin, 3 layers: pith and pigmented cortex and outer cuticle
Eccrine
sweat gland, secrete watery sweat for evaporative cooling
Apocrine
sweat gland, secret milky fluid, embedded deep in dermis, open into hair follicles
Sebaceous glands
associated with hair follicles, release sebum (an oily secretion of fat-filled cells)
Mammary glands
epidermal tissue, develop as mammals become reproductively mature, expand during pregnancy and lactation
Estrous cycle
female fertility cycle, mono or poly
Monoestrous
single estrus during season
Polyestrous
multiple estrus during season
Menstruation
periodically shedding uterine lining (endometrium) after ovulation, only occurs in Old World monkeys and humans and elephants and shrews
based on reproductive and developmental patterns
How are mammals divided into groups?
Subclass Prototheria (monotremes)
oviparous, "single opening", a cloaca, lack nipples, milk is lapped from hair
Subclass Theria
marsupials, viviparous, born very immature, develop in maternal pouch, early embryos enclosed in shell and hatch in uterus, embryos do not implant in the uterus but are supported by a pit digested in the choriovitelline placenta
Subclass Theria
placental mammals, viviparous, prolonged gestation, embryos initially supported by a choriovitelline placenta but later development relies on a chorioallantoic placenta
Gestation length
marsupials < placentals
Lactation time
marsupials > placentals