Radiata lochotrophozoa I

1. RadiatalochotrophozoaI BIOL240.002 Zoology 6 October 2014

2. Radiata

3. Phylum Cnidaria“nettles”—9000+ (9747) spp. cnidarians • Most marine, some freshwater • Radial symmetry • Simple nerve net • Few complex sense organs • Two body plans: • Polyp(often colonial) • Medusa • Three layers • Epidermis • Gastrodermis • Noncellularmesoglea • Cnidocytes • Dioecious with gamete release to the water Fig. 7.3 p. 133 Fig. 7.4 p. 134

4. Cnidarian Systematics and Taxonomy 48 spp. 1 order 36 spp. 2 orders 5945 spp. 10 orders 192 spp. 3 orders 3526 spp. 7 orders Fig. 7.1 p. 132

5. Class Anthozoa—sea anemones and corals“flower animal” Fig. 7.22 p. 145 • No medusa stage • Solitary (anemones) or colonial (corals) polyps • Coral polyps secrete CaCO4 or gorgonin exoskeleton • Zooxanthellaemutualisticin corals • Septategastrovascular cavity • Dioecious • External or internal fertilization • Ciliated larvae Fig. 7.21 p. 144 Fig. 7.20 p. 144 Fig. 7.25 p. 146 Fig. 7.24 p. 146

6. Class Staurozoa—stalked jellyfishes“stake animal” • No medusa stage • Solitary polyps • 8-armed, medusa-like crown of tentacle groups Fig. 7.18 p. 143

7. Class Scyphozoa—true jellyfishes“cup animal” • Medusa stage predominant • 4 oral lobes and 4 gastric pouches internally • 4 rhopalia: statocysts and ocelli • Scyphistoma undergoes strobilation (unique cup-in-cup budding) • Buds off ephyrathat become medusa stage • Dioecious with 4 sets of gonads in the gastric pouches Fig. 7.17 p. 142 Fig. 7.15 p. 141

8. Typical Scyphozoan Life Cycle:EggLarvaePolypstrobilaSexual medusa Fig. 7.16 p. 142

9. Class Cubozoa—box jellyfish“cube animal” • Inconspicuous polyp stage • Medusa: Four tentacles, each with a pedalium • Eyes and other sense organs in rhopalia Fig. 7.19 p. 143

10. Class Hydrozoa—hydrozoans“water animals” • Freshwater hydras, hydroid colonies, floating siphonophore colonies, hydrocorals • Polyps predominate in life cycles (esp. in colonial forms) • Tiny medusae are sexual stage • Hydras: no medusa • Some spp. have no polyp stage • Polyp colonies may have division of labor among different polyps Fig. 7.8 p. 138 Fig. 7.13 p. 140 Fig. 7.14 p. 141

11. Typical Hydrozoan Life Cycle:EggLarvaePolypcolonySexual medusa Fig. 7.10 p. 139

12. Phylum Ctenophora“comb bearer”—~150 (131) spp. comb jellies • Radial symmetry • Swimming or creeping marine animals • 8 rows of cilated comb plates • Two adhesive (non-stinging) tentacles • Mouth, 8 gastrovascular canals, and double anus • Many bioluminescent • Simultaneous hermaphrodites with generally external fertilization and larval stage Fig. 7.31 p. 150 Fig. 7.30 p. 149 Fig. 7.32 p. 150

13. BilateriaProtostomiaLophotrochozoa

14. Phylum Acoelomorpha“without cavity form”—~350 (388) spp. acoelomorphs • Worms formerly considered platyhelminths • Acoelomate (blastocoel fills with parenchyma) • Some with simple gut with no anus • Others wrap around food, forming a temporary gut • Radial nerve net • Asexual fragmentation • Monoecious with copulation HANDOUT

15. Phylum Platyhelminthes“flat worm”—??? (9164) spp. flat worms • Acoelomate (body cavity filled with undifferentiated parenchyma cells) • Free-living in 1 of 4 classes, rest parasitic • Mouth only, no anus (no mouth in tapeworms) • Flattened body • Two nerve cords with anterior ganglia • Protonephridia Fig. 8.1 p. 155 Fig. 8.8 p. 160

16. Platyhelminth Systematics and Taxonomy 2765 spp. 8 orders 2703 spp. 8 orders 2075 spp. 9 orders 1617 spp. 18 orders Which class is para- phyletic, as shown? Fig. 8.3 p. 157

17. Class Turbellaria—turbellarian flatworms“like bustle” • Most free-living • Locomotion via cilia and muscles • Two anterior ocelli • A few parasitic • Asexual reproduction via fission and regeneration • Most monoecious • Penis fencers • Freshwater: mostly direct development • Marine: ciliated larva Fig. 8.4 p. 158 Fig. 8.9 p. 161

18. Class Trematoda—digenetic flukes“hole form” • Internal flukes of vertebrate primary hosts • One or more intermediate hosts • Syncyticalintegument • Lots of mitosis, no cytokinesis • Monoecious • Multiple larval stages: • Swimming miracidium • Asexual parasitic sporocyst • Asexual parasitic redia • Swimming cercaria • Encysted metacercaria • Alternate class name: Digenea (“two origins”) • Largest of 3 subclasses in Hickman et al. Fig. 8.10 p. 162

19. Class Monogenea—monogenetic flukes“single origin” • External flukes of fish skin and gills • Hooks for attachment on posterior opisthaptor “behind fasten” • Syncytial integument • Single hosts in life cycle • Monoecious • Ciliated larva finds new host Fig. 8.13 p. 164

20. Class Cestoda—tapeworms“girdle form” • Scolex with hooks and suckers anteriorly • Long series of proglottids • No digestive system • Syncytial integument • Monoecious • Eggs shed in feces • Larvae embed in intermediate host muscles Fig. 8.14 p. 165 Fig. 8.16 p. 166

21. Typical Tapeworm Life Cycle Fig. 8.17 p. 167

22. Phylum Gastrotricha“stomach hairs”—~460 (838) spp. gastrotrichs • Freshwater and marine • Interstitial • Most <0.5 mm long (to 3 mm) • Acoelomate • Ventral cilia • Scaly, spiny cuticle • One or more pairs of posterior adhesive tubes • Complete digestive tract • Protonephridia • Simultaneous hermaphrodites • Many parthenogenic, with nonfunctioning testes Fig. 8.19 p. 168

23. Phylum Gnathostomulida“jaw little mouth”—80+ (97) spp. gnathostomulids • Marine interstitial animals • Up to 2 mm • Pair of jaws • Mouth; no anus? • Possible temporary or vestigial structure • Acoelomate • Ciliated • Monoecious • Simultaneous or protandrous • Penis only in spp. of 1 of the 2 orders • Hypodermic impregnation or sperm bores through integument • Oviparous with direct development Fig. 8.20 p. 168

24. Phylum Micrognathozoa“little jaw animal”—1 (1) sp. micrognathozoan • Discovered on moss in a spring on Disko Island, Greenland, in 1994 • Microscopic(~140 m)and interstitial • Three pairs of jaws • Thick dorsal epidermal plates • More flexible lateral plates • Cilia on head and venter • Can glue themselves in place • Complete digestive tract • Female only? Monoecious? Fig. 8.21 p. 169

25. Phylum Rotifera“wheel bearer”—~2000 (2014) spp. wheel animals • Mostly freshwater, some marine, some parasitic • Mostly interstitial and floating spp. (to 3 mm, mostly <0.5 mm) • Few colonial spp. • Ciliated corona and grinding or pinching mastax • “crown” and “chew” • 1-4 sticky toes • Syncytical epidermis • 900-1000 nuclei; number is species-specific (eutely) • Complete digestive tract • Pair of protonephridia • Dioecious, but with many parthenogenic spp. • Amictic and mictic eggs • Periodic nonfeeding 1N males Fig. 8.22 p. 170

26. Phylum Acanthocephala“spine head”—1100+ (946) spp. spiny-headed worms • Parasites of vertebrate intestines • Retractibleproboscis with hooks for anchoring • Paired lemnisci control eversion hydrostatically • Retractor muscles pull in • No digestive tract • Syncytial integument absorbs food • False body cavity • Dioeciouscopulators • Acanthor larval stage leaves via host feces and encysts in hemocoel of invertebrate intermediate host that ingests it Fig. 8.23 p. 171

27. Phylum Mesozoa“in the middle animal”—??? (113) spp. mesozoans • Two groups of invertebrate parasites: • 1) Cephalopod mollusk nephridia • 2) Various marine invertebrates • 20-30 cells in outer somatic and inner reproductive layers • No digestive tract • Reproductive cells perform both asexual and sexual reproduction • Larval stages for both Asexual Sexual HANDOUT