CH 33- intro to invertebrates
Terms in this set (100)
Why are sponges not considered "true" animals (eumetazoans)? (In what two fundamental ways are sponge bodies different from the bodies of eumetazoans?)
Sponges lack true tissues
They have no symmetry
Where do sponges live?
How does this relate to how they feed?
Sponges are aquatic, sedentary
- mainly marine
They are filter feeders
What do sponges eat?
How does a sponge capture and ingest food? (Relate this to its anatomy.)
How does a sponge distribute nutrients throughout its body?
Why would you never find a terrestrial sponge?
- Sponges eat tiny particles of food in water
- sticky fibers catch food as it flows through
- Sponges feed by phagocytosis
-CHOANOCYTES trap & ingest food
- AMOEBOCYTES distribute nutrients
- you would never find a terrestrial sponge because they rely on water flow to obtain food.
Describe the sponge body.
Why is it that the layers of cells in a sponge are not really true tissues?
How does the lack of tissue-level organization affect the way sponges live?
- lacks true tissues; digestion & gas exchange happen by diffusion across cell membranes.
- Epidermis- outer layer, tightly packed
- Mesohyl- separatory, gelatinous layer
- Pores- water enters through
- Choanocytes- flagellated cells; engulf food by
phagocytosis; create current
- Amoebocyte- use pseudopodia to transport nutrients;
produce materials for skeletal fibers(spicule) or
more flexible ones (chitin); and can become any
type of sponge cell needed(TOTIPOTENT)
- Spicule- skeletal fibers made od CaCO3 or silica
- Spongocoel- central cavity
- Osculum- water exits here
How are sponge bodies supported?
Supported by hard spicules and protein fibers(spongin) that are made by amoebocyte in mesohyl
How do sponges reproduce?
How do they disperse to new locations?
Why are poriferans sessile as adults?
- Sponges reproduce by fragmentation
- are sexually hermaphroditic
gametes form without gonads
flagellated swimming larvae, sessile adult
- Sponges disperse bc larvae swim w flagella
- Sessile as adults bc they pick a substrate and stay.
In what habitats could you find cnidarians and ctenophores?
Cnidarian and ctenophore are aquatic.
Why are Cnidaria and Ctenophora called "eumetazoans" when the Phylum Porifera is not?
In what two fundamental ways are the bodies of cnidarians and ctenophores different from most eumetazoans (the bilaterians)?
- Cnidaria and ctenophora are "eumatozoan" because they have true tissues & radial symmetry.
Bodies differ from most eumatozoan(bilateria) in:
1. RADIAL SYMMETRY
2. GASTROVASCULAR CAVITY(one opening)
3. Have oral and aboral but no front and back
How does the symmetry of cnidarians relate to their mode of feeding?
Sit & wait carnivores:
- Cnidarians use stinging tentacles around mouth to capture prey with cnidocytes.
- Radial symmetry so all around approach
Compare and contrast the body plan of a cnidarian in its polyp and medusa forms.
What is the fundamental difference in these forms?
POLYP(up) IS SESSILE MEDUSSA(down) IS MOBILE
-Mouth/anus & surrounding tentacles UP
-adhere to substrate by aboral end.
- has body stalk around epidermis
- ex: hydras and sea anemones.
- by passive drifting & contractions of bell-shaped body.
-mouth/anus & surrounding tentacles DOWN
- resembles flattened, mouth-down version of polyp
- ex: free-swimming jellies
- mouth/anus: opening of gastrovascular cavity.
- tentacle: stingers; armed with cnydocytes; arranged in ring around mouth to capture prey & push food into GV cavity.
- Gastrovascular cavity: central digestive compartment; digestion begins here.
- gastrodermis: inner layer body wall(from endoderm);
digestion finishes in food vacuoles contained here.
- mesoglea: gelatinous layer b/w epidermis and gastrodermis
- epidermis: outer layer of body wall(from ectoderm)
How do cnidarians obtain food?
What special adaptations make this possible?
1. Capture prey with tentacles
2. use tentacles to push food into gastrovascular cavity.
3. enzymes secrete into cavity to break down prey into nutrient-rch broth.
4. cells lining cavity absorb nutrients & complete digestive cycle.
5. any undigested remains expelled through mouth/anus.
Tentacles are lined with CNIDOCYTES
- cells unique to cnidarian
- functions: defense, prey capture.
-contain: CNIDAE- capsule-like organelles capable of exploding out
-specialized cnidae: NEMATOCYST- contain stinging thread that can penetrate body wall of cnidarian's prey.
- other cnidae: long threads that stick/entangle prey
Describe how cnidarians ingest and digest their food? How do they get rid of undigested food?
-Tentacles catch prey and push into gastrovascular cavity
-enzymes are secreted that break down prey into nutrients which are absorbed by cells lining gastrovascular cavity.
- any undigested remains are expelled through anus/mouth
How do cnidarians distribute nutrients throughout the body?
"-vascular" Gastrovascular cavity distributes nutrients through body
How do cnidarian cells get the oxygen they need and get rid of carbon dioxide?
Diploblastic: mesoglea in between layers (epidermis & gastrodermis)
there is DIRECT o2/co2 exchange between cells and water.
How do cnidarians move about? Describe their nervous system.
Cnidarians movement is coordinated by a NERVE NET.
-Medusae(jellyfish) swim by BELL contractions.
- power stroke: propulsive jet.
- recovery stroke: water&food drawn in
They have NO BRAIN
- the non centralized nerve net is associated with sensory structures distributed throughout body. (epidermis and gastrodermis have CONTRACTILE CELLS coordinated by net); animal can detect and respond to stimuli all around it.
Using the colonial Hydrozoan Obelia as an example, describe the typical cnidarian life cycle.
Why is this not an example of alternation of generations as in plants?
Alternating stages: polyp-asexual; medusae-sexual(releases eggs and sperm)
1. colony of interconnected polyps(2n) results from asexual reproduction by BUDDING
a. some of the colony's polyps, equipped with tentacles*
, are specialized for
b. the other polyps, *
specialized for reproduction,
*lack tentacles and produce tiny medusa(2n) by asexual BUDDING
2. Medusa swim off, grow, and reproduce sexually.
3. Gonad releases HAPLOID egg(n) (or sperm, depends) which undergoes Meiosis in SEXUAL REPRODUCTION
4. Sperm FERTILIZES egg to form DIPLOID zygote(2n).
5. Zygote develops into solid ciliated larva called a PLANULA(2n)
6. Planula eventually settles and develops into new POLYP(2n)
This is not alternation of generations because it isn't an alternation between haploid and diploid stages. its an alternation between polyp and medusa forms. only the gametes represent a haploid stage.
Name and describe common examples of the different classes of cnidarians. (2 major clades ***)
What kinds of cnidarians have secreted exoskeletons?
****MEDUSAZOAN: produce medusa
- Scyphozoan(JELLIES)- marine&free-swimming, important food for sea turtles
*majority medusa; coastal have brief polyp stage while those in open ocean usually don't have a polyp stage at all; nematocyst bearing tentacles; many are bioluminescent-- generate light used as black light
ex: mice genetically modified with GFP (green fluorescent protein)
ex: portuguese man-of-war(colony of polyps, marine)
- Cubozoan(BOX JELLY)- eyes but no brains or nerves
*majority medusa, box-shaped medusa, most live in tropical oceans & are equipped with HIGHLY toxic cnidocytes.
ex: SEA WASP- highly toxic marine box jelly 'Chironex'; 1 of deadliest organisms.
alternate between polyp and medusa;
ex: OBELIA(drew life cycle), HYDRAS (freshwater, ONLY in polyp form); polyp stage here- colony of interconnected polyps
*****ANTHOZOAN: exist only as polyp.
- Sea Anemone: *marine, solitary, no skeleton
- Coral: *marine, solitary or mostly colonial, secrete CaCO3 exo. for external support
Eeach generation builds on skeletal remains of earlier generations
Coral reef ecosystems are highly diverse and important nurseries for economically important fish*; as important as rainforests are to tropical land. destroyed by pollution, over harvesting and ocean acidification.
ex: star corals- live as colonies of polyps, soft bodies enclosed at base by hard CaCO3 exoskeleton.
ex: SOFT corals- secrete protein-based support structures. ex: sea fan & whip coral.
How are ctenophores different from and similar to cnidarian medusae in anatomy?
- ctenophore have DISTINCTIVE 8 combs of cilia;
- move with 8 comb-like cilia plates whereas cnidaria move with contractile cells and simple net of nerve cells
- use cells capture prey instead of tentacles.
Similar- to cnidarian medusa in
- they have clear medusa-like body
- they can swim (motile)
- have tentacles(2)
- sticky thread for prey
- both "sit and wait" carnivores
eject a sticky thread to capture prey, whereas cnidarians use stinging tentacles
to do so.
How are ctenophores similar in lifestyle to jellies?
both marine "sit & wait" carnivores; motile
How does ctenophore locomotion differ from jellies?
Ctenophore use 8-ciliated plates to swim
Jellies- use contractile cells coordinated by simple net of nerve cells- aka swim by contractions of bell (power stroke for propulsion jet and recovery stroke where water and food into subumbrellar space)
How does the way ctenophore capture food differ from the cnidarians?
Ctenophore capture food when CELLS eject sticky thread
Cnidarians use stinging tentacles with nematocysts to do so.
How does the anatomy of a typical free-living flatworm compare to a cnidarian's body?
How are their digestive systems similar?
Cnidarian: radially symmetric, diploblastic
Flat worm: bilaterally symmetric, triploblastic
Digestive tracts both-
- gastrovascular cavity (1 opening)
Since a flatworm does not have a circulatory system, how is gas exchange and metabolic waste removal handled?
How are nutrients from food distributed?
- Gas exchange and metabolic wastes are both removed by DIFFUSION across surface.
- nutrients from food distributed through gastrovascular cavity
Describe the planarian nervous system & compare it to the cnidarian's.
cnidarian nervous system- NET of nerve cells
planarian nervous system:
simple nervous system,
- eyespots, ganglia, ventral nerve cords
- with eye spots, a BRAIN and muscles planarians can actively avoid light (negative photo taxis)
How does a free-living freshwater flatworm maintain water balance?
Would you expect to find flame cells in a parasitic fluke? Why or why not?
They maintain water balance using:
PROTONEPHRIDIA** WITH FLAME BULBS
tubules with flame bulbs that pull fluid through branch ducts opening to outside
flame bulbs in flukes- no
wouldn't want host blood as fluid for osmosis, used for food
What are the major groups of flatworms, and how do they differ in life-style?
turbellaria-free living carnivores/scavengers
Trematoda(flat worm)-Flukes, Parasitic on animals;
ex: chinese liver fluke- cycles thru human, snail, fish hosts
ex: Blood Flukes (SCHISTOSOMA)- causes schistostomatis
Cestoidea- tapeworms, parasitic on vertebrate intestine; no mouth or digestive system -- ABSORPTIVE; repeated proglottid (sacs of sex organs) lead to posterior scolex(attachment)
Describe each step of the Schistosoma blood fluke life cycle, identifying the two hosts needed to complete its life cycle. Explain why Schistosoma is important to humans & how they get infected.
Schistosoma blood fluke need: human and snail host
1. Mature fluke inside human
2. Sexual reproduction bw male & female fluke
3. Eggs are released in blood stream, causing tissue damage
4. Feces---- eggs here hatch as larvae
5. If eggs reach water, they attach to snail host
6. Undergo asexual reproduction in snail
7. New motile larva develops
8. Larva swim through water to burrow into human's skin
Schistosoma causes schistosomiasis
Where do tapeworms live? What anatomical features of tapeworms are uniquely adaptive for a parasitic existence?
- Tapeworms live primarily in invertebrate intestine
- have no mouth or digestive system=ABSORPTIVE
- Have an anterior scolex for attachment &
- repeated reproductive segments called proglittids
Describe the rotifers and how they live.
Why might they be mistaken for a protist?
microscopic, cylindrical, free living, pseudoceolomate, aquatic, rotating wheel "crown" of cilia brings plankton to mouth
may be mistaken for protist because of how microscopic & free-living aquatic
Where do the rotifers get their name?
Latin meaning "wheel-bearer"; reference to the crown of cilia that brings a vortex of water into the mouth
How is their digestive system different from the flatworms?
What adaptive advantage does the mouth- to-anus digestive tract have compared to the gastrovascular cavity?
Rotifers have an alimentary canal: TWO holes for mouth and anus.
Mouth-to-anus digestive tract is advantageous because
there's flow thru food processing
specialized digestive regions
* allows for step wise digestion of a wide range of food particles
How are nutrients distributed in a rotifer's body?
Nutrients are distributed by the pseudocoelom.
Fluid here acts as hydrostatic skeleton, when rotifers body moves it distributes this water throughout the body.
What unusual form of reproduction is seen in some rotifers?
development of an embryo from an unfertilized egg
What features are shared by the two lophophorate phyla (ectoprocts and brachiopods)?
"LOPHOPHORATES"(ectoproct & brachiopod)
- aquatic, sessile, suspension feeders using lophophore, - u-shaped alimentary tract
- no head
- true coelom
What is the function of the lophophore?
How is this structure different from cnidarian tentacles? Why is a U-shaped digestive tract an adaptation to feeding with a lophophore?
- horseshoe ring of mucus-coated ciliated tentacles around mouth; function: SUSPENSION FEEDING; cilia draws in water toward mouth & tentacles trap suspended food particles
- CNIDARIAN tentacles are stinging & catch prey with CNIDOCYTES; loofa-trocho go through distinctive trochophore larval stage
- U-shaped digestive tract is an adaption bc lophophore are horse shoe shaped, u shaped tract fits to spread nutrients through entire structure
Why do you think the ectoprocts were commonly called "bryozoans" or "moss animals"?
- mineralized skeleton
A colony of bryozoans might easily be confused with what other sort of colonial marine invertebrate?
How could you tell them apart?
Could be confused with CNIDARIAN//coral bc bryozoan contribute to reefs?
You could tell them apart bc brazen have lophophore!
Brachiopods might easily be confused with what other marine animals?
How could you tell them apart?
Are brachiopods more common or less common than them?
- brachiopods"lampshells" easily confused with marine bivalve mollusk(but these 2-shells are analogous structures)
- You could tell them apart because brachiopods have lophophore!!!!
What are the three basic parts that all mollusks have? What are their functions?
Mollusc all have:
- Mantel: covers visceral mass; forms pearls/shell if present; form mantle cavity w/ gills or lungs for gas exchange.
- Visceral Mass: contains internal organs (open circ. system)
- Foot: locomotion and digging
Identify the organs and organ systems of mollusks. How do most mollusks deal with ingestion, digestion, metabolic wastes, gas exchange, and distribution of nutrients?
Inside Visceral Mass:
- Open Circulatory System(circulating fluid also bathes tissues)(heart pumps hemolymph through arteries)
-Gill(leaf-like)(inside mantle cavity) -> heart
-Mouth(radula 4 feeding) ->Coiled Digestive tract->
anus(out of mantle cavity)
- Nervous System:
- nerve ring around esophagus -> nerve cords extend through foot
Mouth with scraping radula
Metabolic Waste(from hemolymph)
METANEPHRIDUIM- excretory organ
Gills or lungs in mantle cavity
Distribution of nutrients
open circulatory system
What is an open circulatory system?
Is there any difference between the fluids pumped by the heart and the fluids bathing the tissue?
Hemolymph fluid circulated through arteries into sinuses and bathes organs continually.
What comprises the shells of mollusks and how are they made?
Hard protective shell made of calcium carbonate in a protein matrix
Secreted by mantle tissue
Is a radula unique to mollusks?
Do all mollusks have a radula?
What does a radula do?
-radula is unique to mollusk
- Many mollusks have a radula
-strap-like FEEDING organ in mouth. belt of backward curved teeth thrusts outward then retracts into mouth, causing a scraping and scooping
If snails (gastropods) do not have separate sexes, then how do they reproduce?
Snails reproduce by: simultaneous hermaphroditism
*rely heavily on chemoception and contact sensation
What is a trochophore larva?
In snails that lay shelled eggs on land, why do you think trochophore larvae are absent?
- Trochophore larva are CILIATED
- In terrestrial snails, trochophore stage is absent because they adapted to egg with calcified shell; no larval stage; can't swim
How can we distinguish among the four major classes of mollusks covered in lecture, just on the basis of external anatomy?
Name some common examples from each class.
GASTROPODA(snails): Largest Class!// Land, f.w., and marine; single shell or no shell; use radula to feed; torsion moves mantle cavity over head-end; head & foot can retract into shell **cephalization
Terrestrial snails(garden snail, slug, tree snail, escargot); predators( venomous cone snail, some land snail);
Fresh Water(schistosomiasis host- aka snail fever); *Marine(texas state sea-shell lightning whelk, conch, cowrie, conch fritters) (marine shell-less: sea slugs and nudi branches)
POLYPLACHOPHORA: 8 dorsal plates from shell; no distinct head; marine intertidal grazers; radula to scrape algae.
BIVALVIA: 2-part shell joined by hinge; no distinct head; FW or marine; suspension feeders; burrowing or sessile; filter with ciliated gills; NO radula
examples: freshwater CLAM(burrows); invasive zebra MUSCLES(have byssus to adhere to rocks); SCALLOP(sessile); Pearl OYSTER
CEPHALOPODA: active marine predators; foot modified into grasping arms & tentacles with suckers; beak-like jaws; well-developed eyes and brain; water-jet propulsion( excurrent siphon and mantle cavity); **closed circulatory system
examples: giant squid; octopus; ammonites (shelled cephalopod during mesozoic/ extinct); nautilus (only living cephalopod with external shell); squid "pen" & cuttlefish (reduced internal shell)
How do the different anatomical features of the different mollusk classes relate to their life-styles (where they live & how they get their food)?
(Think of modifications to the shell & foot, feeding apparatus, locomotion, sensory organs, etc.)
CHITON(polyplach): marine intertidal grazers
GASTROPOD: land, freshwater, AND marine; some graze on plants, algae, bacteria; some are predators (have siphon w/ harpoon, a tubular sucking organ), parasitic
BIVALVIA: fresh water or marine; mantle modified into siphon for burrowed; digging foot; suspension feeders(burrowing or sessile)
CEPHALOPODA: active marine; predators (modified foot, jaws)
Which class of mollusks has diverse representatives on land?
Which classes are exclusively marine (in saltwater environments)?
Gastropoda have diverse representatives on land
Chitin(polyplachophora) & cephalopod are EXCLUSIVELY MARINE
How does torsion help gastropods to be successful? How does this relate to the fact that this group is successful on land?
Torsion helps gastropods move mantle cavity over head(head and foot can retreat into shell) (=spiraled shell)
- bc they move so slow they're vulnerable to attack; being able to retreat into shell when threatened
- in terrestrial: ventilation is better with anterior positioning of mantle cavity
Explain why almost all bivalves are either burrowing or sessile.
Why don't they have heads?
Bivalves are either burrowing or sessile because they
1. lead sedentary life styles
2. are suspension feeders who bring in water(& food) through excurrent siphon
They're heads aren't distinct.
What adaptations of cephalopods relate directly to their predatory lifestyle?
Adaptions for cephalopod predation:
- beak-like jaws
- poison in saliva
- foot modified into grasping arm/tentacle with suction
used to grasp prey
ability to learn & behave benefits predators
jet propulsion & steering
How are the various mollusks of economic importance to humans?
Mollusca economic importance:
- people eat:
-land snails(escargot) & marine snails(conch fritters) (gastropoda); oysters & muscles (bivalve); squid mantle (calamari) & octopus (cephalopoda)
- human cultures have depended on bivalves for food for thousands of years
What combination of features distinguishes annelids from all other phyla?
(Is there a SINGLE feature that distinguishes them from other animals?
-segmentation=external & internal features are repeated (reduced in leeches)
-soft body: segmented true coelom acts as hydrostatic skeleton
-well-developed organ systems: (closed circulatory system)
What is segmentation and why is it an advantage for these worms to be segmented?
What other invertebrate phyla are segmented?
- external and internal features are
repeated; helps with
locomotion; segmented true coelom acts as *hydrostatic skeleton
- arthropods are also segmented
How does a segmented coelom contribute to annelid locomotion?
segmented coelom acts as HYDROSTATIC skeleton
Identify the organs and organ systems of annelids.
How do annelids deal with ingestion, digestion, circulation and gas exchange, and disposal of metabolic waste?
Closed circulatory system
- blood and tissue fluid are separate
- dorsal and ventral vessels linked by segmented vessels, some are muscular used to PUMP BLOOD through circulatory system,
Respiratory Organ- skin
- gas & nutrient exchange is across CAPILLARY BEDS
-for indigestion/digestion: mouth, esophagus, intestine, & anus
- METANEPHRIDIA- excratory tubules
- brain-like pair of ganglia above front end of pharynx(ring of nerves connect to sub-pharyngeal ganglion which fused pair of nerve cords runs posteriorly)
How does the closed circulatory system of an earthworm differ from the open circulatory system of a snail?
How are they similar?
Is there any difference between the fluids pumped by the heart and the fluids bathing the tissue?
Where does exchange ( of nutrients, wastes, and gases) with the tissues occur?
CLOSED CIRC SYSTEM: blood & tissue are SEPARATE
- Fluid pumped by heart: blood
- Fluid bathing tissue: interstitial fluid
Exchange with the tissues occurs across CAPILLARY BEDS
How do marine worms disperse widely to new locations?
What adaptation permits earthworms to reproduce successfully in terrestrial environments?
- Marine worms disperse in their TROCHOPHORE LARVAL stage
- Earthworms can reproduce successfully in terrestrial environments b/c ::
- DIRECT DEVELOPMENT(just grow in size)
- mucus for mvmt through soil
What are the major types of annelids and their characteristics?
Explain how their features relate to their lifestyles.
- fleshy parapodia & many bristles; all marine; trochophore larvae
- examples: *bristle worms(active predators w/ jaws; fleshy parapodia and chitinous bristles)
- & *fan-worms (sessile suspension/deposit feeders; live in tubes or burrows; obvious lophophore)
- w/ few bristles & no parapodia; reduced head; terrestrial or freshwater;deposit feeders
- example:. *earthworms-eat dirt, aerate soils
- fresh water predators or blood-sucking parasites(ANTI-COAGULANT); no bristles; no parapodia; sucker at both ends; anti-couglant; some on land
In what ways are annelids of economic or health importance to humans?
Oligchaeta(EARTHWORMS): soil aeration, eat dirt
HIRUDINEA(leeches): used for medicine as anti-couglant; fish bait (earthworms)
What features do all arthropods have in common that distinguish them from other phyla?
-segmented body w/ hard exoskeleton & jointed appendages (highly specialized regions)
-tough cuticle made of chitin & proteins
-open circulatory system
What are the three main regions of the body?
For which functions are these regions specialized?
Head- eyes, antenna
THORAX- d legs
ABDOMEN- swimming appendages; one for each abdominal segment
What comprises the exoskeleton (cuticle)?
Why is the exoskeleton of a crab harder than the exoskeleton of a cockroach?
How is the exoskeleton of arthropods adaptive for land life?
- arthropod exoskeleton is made of CHITIN & PROTEINS
- Exoskeleton hardened in MARINE sp w/ CaCO3
- land spp w/ waxes to reduce H2O loss.
- waxes reduce water loss; limited growth; sheds by molting(ecdysis) to grow.
How is the arthropod exoskeleton limiting?
- limits body size
- must be shed to grow
Describe the circulatory system of arthropods.
What is the difference between hemolymph and blood?
OPEN circulatory system;
- hemolymph: fluid that is propelled by heart pumped in vessels and into sinuses and bathes tissues
- blood: stays in blood vessels and doesn't bathe tissues
What are the different modes of gas exchange among the arthropods?
Which modes depend on the circulatory system and which mode does not?
-Aquatic: have gills with feather extensions
-Spider's hemolymph flows thru book lungs in contact w/ air
- Insects: trachea takes air DIRECTLY to cells
CIRCULATORY SYSTEM NOT INVOLVED IBN GAS EXCHANGE IN INSECTS
How does body plan differ between these subphyla: Trilobites, Chelicerates, Myriapods, Hexapods, and Crustaceans?
TRILOBITES(extinct): many simple appendages and segments.
CHELICERATES(spiders): cephalothorax + abdomen; no antennae
MYRIAPODS(-pedes): many identical segments & legs; 1 pair antennae
HEXAPODS(insects): body in 3 regions(abdomen, thorax, head); thorax w 1 or 2 pair of wings from dorsal side; head-antennae, compound eyes, mandibles; and mandibles
CRUSTACEAN(crab, lobster, shrimp, krill, barnacles, water flea, copepod, roly-poly ): 2 pair antennae; many *branched legs on thorax & abdomen
What are trilobites?
When and where did they live?
What arthropod features do they have?
- early marine group of arthropods
- highly diverse (all extinct now)
-highly marine group
- many simple appendages and segments; diversity of form
Describe chelicerae and how they function.
- claw-like appendages used for feeding
- poisonous fangs in spiders
- only chelicerates have them as mouthparts(spider, horse-shoe crab)
What were the earliest chelicerates like?
What kinds of marine chelicerates exist today?
What habitats do the greatest diversity of chelicerates occupy today?
What is the biggest group of chelicerates today?
- Marine & Fresh water "euryptenids" aka water scorpion (chelicerate not scorpion)
Marine Chelicerates today:
- horse-shoe crab(chelicerate not crab) and sea spiders(chelicerate not spider)
MOST chelicerates today are
- LAND predators or parasites
What are the major types of arachnids and what are their ecological roles (predator, herbivore, parasite, decomposer)?
Major types of arachnids & roles:
- predatory scorpion & spider(black widow, brown recluse)
-parasitic ticks and mites (tick, dust mites, plant mite, human follicle mites)
-other arachnids: (daddy-long-legs, camel spider or sun spider, vinegaroon or whip scorpion, etc.)
How are the two types of myriapods similar in body plan?
How do they differ in body plan and ecological roles? Where do we find centipedes & millipedes?
-mandible for feeding; 1 pair antennae & all terrestrial; many identical segments and legs
-millipedes: PLANTS detriver/herbivore; *scavengers & have 2 pairs of legs per segment,
-centipedes: MEAT carnivores; *predators & have 1 pair of legs per segment w/ 'poison claws'
Where are you most likely to find a crustacean?
mostly marine and some freshwater (AQUATIC)
How are crustaceans anatomically different from insects and arachnids?
2 pair antennae
feed with MANDIBLES
BRANCHED legs on thorax and ab
What are the major ecological roles of crustaceans?
predators & scavengers
List some examples of marine, freshwater, & terrestrial crustaceans.
MARINE: crab, lobster, shrimp, krill, barnacles,
FRESHWATER: water flea, planktonic copepod(most numerous of all animals)
TERRESTRIAL: Roly poly
Where do insects live?
insects are extremely successful on land
many in freshwater
Describe the anatomy of an insect.
What method of insect locomotion is found in no other invertebrate?
- thorax: 0-2 pair of wings from dorsal side
- head: pair antennae, compound eye
- MANDIBLES for eating
First animals to fly!!!
What unique adaptations do insects have for disposing of metabolic wastes and doing gas exchange in the terrestrial environment?
For EXCRETION of metabolic wastes
-unique tracheal system
How do insects feed?
What do they eat?
What are the ecological roles of insects?
- they use MANDIBLES for feeding
- they have diverse feeding habits/ecological roles: herbivores, predators, parasites, decomposers, etc.
What adaptations do insects have for reproduction in the terrestrial environment?
Land-adapted reproduction: many do metamorphosis
What are the most important ways insects affect the lives of humans?
-breakdown organic materials
-make some areas livable
-important in food webs
-help/injure other elements of ecosystem
-spread disease & pollen...
What features distinguish nematodes from other wormlike phyla?
What anatomical feature do they share with other ecdysozoans?
-colorless round body w/ tapered ends
- no segmentation
-w/ thick, flexible cuticle (outer coat) that is SHEDS AS IT GROWS (ecdysis)
-well developed digestive tract (ALIMENTARY CANAL), gonads, and nerve cords
-pseudocoelom DISTRIBUTES NUTRIENTS
What organ systems do nematodes have?
What allows these animals to function with no circulatory system, no respiratory system, and no excretory system?
well developed DIGESTIVE TRACT; gonads; nerve cords
Pseudocoelom allows these to function
- distributes nutrients
- DIRECT GAS EXCHANGE
How does the pseudocoelom contribute to locomotion?
Where can nematodes be found?
What are the important ecological roles of nematodes? Relate this to the degree of cephalization in nematodes.
- free-living DECOMPOSERS in soil
- PARASITES in plants and animals
What are some important examples of roundworms that parasitize animals?
ANIMAL ROUNDWORM PARASITES:
- TRICHINA worm:causes trichinosis from eating undercooked pork
- Dog intestinal round worm(carried by rats)
- Dog heart worm(by mosquito bites)
- Dog HOOKworm
- Human PINWORM
-LOA LOA WORM in africa carried by DEER FLIES
- FILARIA worm- mosquito bites
What does a velvet worm look like and where do they live today?
VELVET WORM AKA ONYCOPHORA
-flexible cuticle w/ chitin (sheds as it grows) & segemented CYLINDRICAL body w/ many legs, but legs are soft and unjointed
- predators in tropical forests
What characteristics do velvet worms have that demonstrate close relationship to Arthropods?
How do they differ from Arthropods?
they have an EXTERNAL CUTICLE THAT SHEDs as it grows and have a SEGMENTED body;
however, their appendages (legs) are UNJOINTED unlike the arthropoda
How do onychophorans obtain food?
What do tardigrades look like?
What features make water bears similar to arthropods? How do they differ from arthropods?
TARDIGRATA AKA WATER BEAR
looks kinda like a gummy bear
-segmented w/ chitonous cuticle that SHEDS
-but w/ 4 pairs of stubby, unjointed legs
-very small (<0.5mm)
-live in water films on plants, soils
Where do tardigrades live & how do they feed?-
- In WATER FILMS on plants and in soil.
- PIERCINGg mouthparts feed on plant/animal cell fluids;
What special property do TARDIGRADES have that make them well-adapted to surviving where they live?
- can survive extreme conditions in a dormant state: dehydrated for years, extreme temperatures, hi/lo pressure, even outer space, radiation
Besides having deuterostome development, what features distinguish echinoderms from the other invertebrate phyla?
- DEUTEROSTOME development
- pentaradial symmetry as adults
- oral/aboral sides; central mouth
- no head; no brain
- bilateral symmetry as larvae
- endoskeleton made of CaCO3 & unique ***water vascular system
- true LARGE coelom (ex: sea urchin)
- can force STOMACH OUT by EVERSION
Describe the external anatomy of a sea star.
Why, even though they have pentaradial symmetry, are echinoderms still considered part of the Bilateria?
- oral/aboral side with mouth and TUBE feet on oral side
- fluid-filled canals and tube feet used for locomotion and feeding
- very decentralized
- water vascular system
- endoskeleton: internal Calcium carbonate plates & spines working w/ muscles (ossicles) to move arms
- still considered bilateral b/c bilateral as larvae
How is the echinoderm body supported?
How is this different from all the other invertebrates so far?
What are the functions of the coelom in echinoderms?
- endoskeleton: internal Calcium carbonate plates & spines working w/ muscles (ossicles)
- Differs with it's WATER VASC. SYSTEM
- COELOM function: CIRCULATORY & DIGESTIVE
- distributes nutrients & helps with gas exchange
- contains the digestive glands
- coelom has openings that lead out to spines forming gills like lobe/balloons
Describe the water vascular system.
What are its functions?
-has fluid-filled canal and tube feet
-function: locomotion and feeding
What two body systems contribute to movement in echinoderms?
Muscular & endoskeleton
Where are echinoderms found?
What might explain why there are no terrestrial echinoderms?
They have a water vascular system; they would dry out in terrestrial environments
Describe and give the common name of the different types of echinoderms.
How do the different types of echinoderms feed?
Asteroidea: SEA STAR ('star fish')
*PREDATORS: eversion of inside of bivalve
Ophiuroidea: BRITTLE STAR
Echiniodea: SEA URCHIN & SAND DOLLAR & SEA
*HERBIVORE & SCAVENGER
Crinoidea: SEA LILIES & FEATHER STARS
**known for: preserved fossils; earliest
echinoderm think sea stars descended from
Holothuroidea: SEA CUCUMBER
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