Fig. 33-1

1. Fig. 33-1

2. Overview: Life Without a Backbone • Invertebrates are animals that lack a backbone (ansence NOT a good character) • They account for 95% of known animal species • Is it a natural (monopyletic group)? • i.e. clade or grade?

3. Fig. 33-2 Major groups “Porifera” (grade) Calcarea and Silicea ANCESTRAL PROTIST Cnidaria Lophotrochozoa Common ancestor of all animals Eumetazoa Ecdysozoa Bilateria Deuterostomia

4. Fig. 33-3-1 Placozoa (1 species) Calcarea and Silicea (5,500 species) 0.5 mm A sponge Cnidaria (10,000 species) A placozoan (LM) Ctenophora (100 species) A jelly Acoela (400 species) A ctenophore, or comb jelly 1.5 mm Acoel flatworms (LM) LOPHOTROCHOZOANS Rotifera (1,800 species) Platyhelminthes (20,000 species) A marine flatworm A rotifer (LM) Ectoprocta (4,500 species) Brachiopoda (335 species) Ectoprocts A brachiopod

5. Fig. 33-3-2 Cycliophora (1 species) Acanthocephala (1,100 species) 100 µm An acanthocephalan (LM) A cycliophoran (colorized SEM) Nemertea (900 species) Mollusca (93,000 species) An octopus Annelida (16,500 species) A ribbon worm A marine annelid ECDYSOZOA Loricifera (10 species) Priapula (16 species) 50 µm A loriciferan (LM) A priapulan

6. Fig. 33-3-3 Tardigrada (800 species) Onychophora (110 species) 100 µm Tardigrades (colorized SEM) An onychophoran Nematoda (25,000 species) Arthropoda (1,000,000 species) A roundworm A scorpion (an arachnid) DEUTEROSTOMIA Hemichordata (85 species) An acorn worm Echinodermata (7,000 species) Chordata (52,000 species) A sea urchin A tunicate

7. Fig. 33-3a porifera A sponge

8. Fig. 33-3b Cnidaria A jelly

9. Fig. 33-3c 0.5 mm A placozoan (LM)

10. Fig. 33-3d A ctenophore, or comb jelly

11. Fig. 33-3e 1.5 mm Acoel flatworms (LM)

12. Fig. 33-3f Lophotrochozoa A marine flatworm

13. Fig. 33-3g Lophotrochozoa A rotifer (LM)

14. Fig. 33-3h Lophotrochozoa Ectoprocts

15. Fig. 33-3i Lophotrochozoa A brachiopod

16. Fig. 33-3j Lophotrochozoa An acanthocephalan (LM)

17. Fig. 33-3k Lophotrochozoa 100 µm A cycliophoran (colorized SEM)

18. Fig. 33-3l Lophotrochozoa A ribbon worm

19. Fig. 33-3m Lophotrochozoa An octopus

20. Fig. 33-3n Lophotrochozoa A marine annelid

21. Fig. 33-3o Ecdysozoa 50 µm A loriciferan (LM)

22. Fig. 33-3p Ecdysozoa A priapulan

23. Fig. 33-3q Ecdysozoa 100 µm Tardigrades (colorized SEM)

24. Fig. 33-3s Ecdysozoa A roundworm

25. Fig. 33-3t Ecdysozoa A scorpion (an arachnid)

26. Fig. 33-3u Deuterostome An acorn worm

27. Fig. 33-3v Deuterostome A sea urchin

28. Fig. 33-3w Deuterostome A tunicate Closer!

29. Concept 33.1: Sponges are basal animals that lack true tissues • Sponges are sedentary animals from two phyla: Calcarea and Silicea • They live in both fresh and marine waters • Sponges lack true tissues and organs

30. Fig. 33-UN1 Calcarea and Silicea Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia

31. Sponges are suspension feeders, capturing food particles suspended in the water that pass through their body • Choanocytes, flagellated collar cells, generate a water current through the sponge and ingest suspended food • Water is drawn through pores into a cavity and out through an opening

32. Fig. 33-4 Food particles in mucus Flagellum Choanocyte Collar Choanocyte Osculum Azure vase sponge (Callyspongia plicifera) Spongocoel Phagocytosis of food particles Amoebocyte Pore Spicules Epidermis Water flow Amoebocytes Mesohyl

33. Sponges consist of a noncellular mesohyl layer between two cell layers • Amoebocytes are found in the mesohyl and play roles in digestion and structure • Most sponges are hermaphrodites: Each individual functions as both male and female

34. Lophotrochozoans, a clade identified by molecular data, have the widest range of animal body forms • Bilaterian animals have bilateral symmetry and triploblastic development • The clade Bilateria contains Lophotrochozoa, Ecdysozoa, and Deuterostomia • Look at your tree!

35. Fig. 33-UN3 Calcarea and Silicea Cnidaria Lophotrochozoa Ecdysozoa Deuterostomia

36. The clade Lophotrochozoawas identified by molecular data • Some develop a lophophore for feeding, others pass through a trochophore larval stage, and a few have neither feature • Lophotrochozoa includes the flatworms, molluscs, and many other important phyla

37. Flatworms • Members of phylum Platyhelminthes live in marine, freshwater, and damp terrestrial habitats • They are flattened dorsoventrally and have a gastrovascular cavity • Gas exchange takes place across the surface

38. Turbellarians • Turbellarians are nearly all free-living and mostly marine • The best-known turbellarians are commonly called planarians

39. Fig. 33-9

40. Fig. 33-10 Pharynx Gastrovascular cavity Mouth Eyespots Ganglia Ventral nerve cords

41. Monogeneans and Trematodes • Monogeneans and trematodes live as parasites in or on other animals • They parasitize a wide range of hosts, and most have complex life cycles • Trematodes that parasitize humans spend part of their lives in snail hosts • Most monogeneans are parasites of fish

42. Blood fluke=schistomiasis Male Female Human host 1 mm Motile larva Ciliated larva Snail host

43. Tapeworms • Tapeworms are parasites of vertebrates and lack a digestive system • Tapeworms absorb nutrients from the host’s intestine • Fertilized eggs, produced by sexual reproduction, leave the host’s body in feces

44. Fig. 33-12 200 µm Proglottids with reproductive structures Hooks Sucker Scolex

45. Molluscs • Phylum Mollusca includes snails and slugs, oysters and clams, and octopuses and squids • Most molluscs are marine, though some inhabit fresh water and some are terrestrial • Molluscs are soft-bodied animals, but most are protected by a hard shell

46. Most molluscs have separate sexes with gonads located in the visceral mass • The life cycle of many molluscs includes a ciliated larval stage called a trochophore

47. There are four major classes of molluscs:

48. Chitons • oval-shaped marine animals encased in an armor of eight dorsal plates

49. Fig. 33-16

50. Gastropods • About three-quarters of all living species of molluscs are gastropods Video: Nudibranchs