1
Zoology 432 Invertebrate Zoology Exam II
Name ________________________
1. What are the classes of Cnidaria and their characteristics? 10
Hydrozoa: hydroid and medusa forms, marine and freshwater, asexual and sexual reproduction
Anthozoa: all marine, only sessile polyp form, construct protective calcareous skeleton, sessile.
Scyphozoa: all marine, polyp and medusa forms, jellyfish, sexual and asexual reproduction.
2. Describe, in detail, the reproduction of one of the Cnidarian Classes. 5
Scyphozoa: asexual = polyp produces scyphistoma
Reproductive = from scphyistoma; zygote from male and female gametes, metamorphoses into
planula larva, settles and matures into polyp, produces Ephyra that mature into medusa form of
jellyfish that are sexual forms producing sperm and egg.
Anthozoa: asexual = fission, pedal laceration
3. Describe sexual reproduction in one of the parasitic flukes. 5
Sheep liver fluke: hermaphroditic, adults in bile ducts exchange gametes, eggs break through
blood vessels into intestine.
Tape worm: hermaphroditic, adults in intestine, exchange gametes, produce eggs that go out with
feces.
4. What is this organism? Label everything on this diagram. 5
Obelia, reproduction polyp, feeding polyp, medusa form (gonads, tentacles, stomach, velum),
zygote, planula larva
5. What class(es) of Cnidarians occur in freshwater? Name two examples (common name or
genera). 5
Scyphozoa: freshwater jelly
Hydrozoa: Obelia, Hydra
6. What are the classes of Platyhelminthes and their characteristics? 10
Turbellaria: free-living flatworms, aquatic benthic flatworms, sexual and asexual repro, single
opening digestive tract, eyes present.
Trematoda: parasitic flatworms, hermaphroditic,no eyes, only sexual reproduction, single
opening digestive tract, adult form is parasitic, complex life cycles with more than one host.
2
Cestoda: parasitic tapeworms, scolex for attachment to host, proglottids contain reproductive
organs, hermaphroditic, no eyes, adults occur in intestine of host where they reproduce by
exchanging sperm.
7. Describe dispersal in the flatworms (Platyhelminthes). 5
Turbellaria: free-living, move on cilia
Cestoda: barely move in intestine, dispersal by eggs w/host feces
Trematodes: dispersal by larval form in water/terrestrial and in intermediate hosts
8. Sketch a detailed life cycle of the one of the parasitic flukes. Label all stages. 10
Tapeworm or liver fluke
9. Label all structures. 5
Proglottid, uterus, nerve cord, vitellarium, ovary, genital pore, nephridial canal
10. Describe the digestive, nervous, and excretory systems of Cestodes. 5
Digestion: none, absorbed through body wall
Nervous: nerve cord runs through proglottids, no eyes present
Excretory system: simple nephridial canal, diffusion
11. Describe the digestive, nervous, and excretory system of Trematodes. 5
One-way gut = no anus, only mouth, digestion in intestine
Cephalization occurs, neurons along sides, eyes present
Nephridial structures for excretion to excretory pore
12. Describe and explain the diversity (taxonomic and biotic diversity) of molluscs. Why are
they so successful? 10
Many classes of molluscs: polyplacophora = chitins, aplacophora, monoplacophora, gastropods
have high diversity, scaphopoda, Bivalvia, cephalopoda.
Successful because they have many body forms from a simple basic plan, inhabit nearly every
biome on planet and have diversity of trophic positions.
13. Describe respiration and digestion in gastropods. 5
Respiration: gilled and lung forms
Digestion: complete mouth to esophagus to stomach to intestine to anus. Digestion and
absorption in stomach and intestine.
3
14. What are Mollusca classes and their characteristics? 10
polyplacophora = chitins, plates on dorsal surface, benthic scrapers
aplacophora = solenogasters, marine worms
monoplacophora = looks like limpet, marine deepwater form
gastropods = mostly shelled, terrestrial and aquatic, have high diversity
scaphopoda = tooth shells, marine benthic form
Bivalvia = clams, two shells, filter feeders, marine and freshwater
Cephalopoda = octopods, nautilus, and squids, highly developed nervous systems, predators,
marine
15. Describe reproduction in Unionidae clams. 5
Dioecious: sperm into water, female brings sperm into mantle cavity with water, fertilization
internal, eggs develop into glochida that are forced out when fish or other host approaches,
glochidia latch onto fish for several weeks and take blood meal, release and drop to sediment to
develop into adult.
16. Label structures. 5
Umbo, muscle scars, cardinal teeth, excurrent and incurrent siphon. Heart, foot, intestine,
stomach, gonad, digestive gland, gill
17. Describe digestion in bivalves. 5 Food particles pulled into mantle cavity
by cilia movement on gills. Particles sorted on gills and stick to mucus that
carries to mouth. Esophagus to stomach – enzymes digest. Intestine
absorption; to anus and out excurrent siphon.