2. Chapter 33

3. Lack a backbone 95% of known animal species Occupy almost every habitat on Earth

4. No True tissues No symmetry Suspension feeders Most are hermaphroditic

7. Radial symmetry All have cnidocytes Diploblastic Gastrovascular cavity (no anus) Carnivorous Body plan: Polyp Medusa Simple muscle system Simple nerve net nervous system, no brain

8. Hydrozoa Alternate polyp and medusa in life cycle, with polyp as dominant stage Alternate polyp and medusa in life cycle, with polyp as dominant stage Examples: colonial hydroids, hydra, Portuguese Man of War Examples: colonial hydroids, hydra, Portuguese Man of War Scyphozoa: Prominent medusa Examples jellyfish Anthozoa: Polyps are dominant Sea anemonies, and coral

9. Lack coelom Bilateral symmetry What evolutionary novelty comes with bilateral symmetry? Cephalization

10. What new novelties are seen in this phylum? Triploblastic, so has muscular system Organs Cephalization, more complex nervous system

11. Turbellaria: Carnivorous Moves by cilia Eyespots on head Rudimentary brain Diffusion for gas exchange Excretion through flame cells Hermaphroditic

14. Often called flukes All members are parasitic What makes a parasite in good standing? Become an egg machine since it is hard to find a host Use intermediate hosts Develop hooks and suckers Hermaphroditism, so that limits need to find others

16. Tapeworms Parasitic Scolex in adult hooks onto the host intestines Proglottids for reproduction Eggs eaten by intermediate host and larva develops Final host infected by eating intermediate host encysted with larva forms Do not eat poorly cooked meats!

21. Not quite a true coelom, missing the inner lining of muscle

22. Mostly marine 1 st to get an anus Organs lie in the pseudocoelom Parthogenesis – unfertilized eggs develop into females

24. Many found in soil, useful for nutrient recycling Complete digestive tract Some are parasitic, e.g. trichinella and hookworm (dogs)

27. Mouth develops from the blastopore Cleavage is radial and determinate ALL HAVE A TRUE COELOM!

28. Bilateral symmetry Open circulatory system Soft bodied, with hard shell protection Most have exoskeletons Reduced or no segmentation Radula; rasping tongue to scrape food True coelom Many internal organs Three body parts Foot Visceral mass Mantle

30. Polyplacophora Chitons Cling to rocks Live on rocky shores Use muscular foot to grip Gastropods Snails, slugs, nudibranchs Largest class Shell protects body Torsion leads to twisted body Uses radula to scrape algae and graze on plants Uses radula to scrape algae and graze on plants

31. Bivalves: Clams, oysters, mussels, scallops Possess shell divided and hinged into two halves Filter feeders Sedentary lifestyle Cephalopods Squid and octopus and nautilus Use jaws to bite prey Mouth as base of foot (foot drawn into several tentacles) Complex brains and capable of learning and moving fast Mantle reduced or absent Can get large, How?

32. SEGMENTATION! Closed circulatory system Alimentary canal Five pairs of hearts Gas exchange across skin Metanephridia for gas exchange Nitrogenous wastes exit from each segment through pores Nervous system with ganglia and ventral nerve cords

33. Oligocheates Earthworms Polycheates: Fanworms Tube dwellers (marine) Hirudinea: Leeches Used to treat bruised tissues and to stimulate circulation Used to treat bruised tissues and to stimulate circulation

34. Coelom Serves as hydrostatic skeleton Developed complex organ system Protects internal structures Segmentation Specialization of body segments

35. Key characteristics: Jointed appendages Segmentation Hard exoskeletons Extensive cephalization Open circulatory system Gas exchange gills in water, book lungs or spiracles on land

36. Successes: Exoskeleton, lets them thrive on land, but limited Jointed appendages allowed for walking and then flying in some More successful organization of segments Limits: Exoskeleton is shed Limited brain size Limited body size

37. Trilobites Extinct group Show pronounced segmentation, with little variation in appendages Show pronounced segmentation, with little variation in appendages Early, primitive arthropods Chelicerates Includes the arachnids 1-2 body segments with 8 legs Uniramia Includes insects, millipedes and centipedes

38. Arachnids Scorpions, spiders, mites Insects 1 pair of antennae 6 legs 3 body segments Crustaceans Crabs, crayfish, lobsters, isopods (pill bugs) 2 or 3 body segments

39. Radial indeterminate cleavage Blastopore becomes the anus

40. Secondarily evolved radial symmetry Unique water vascular system Has mouth and anus Has endoskeleton

41. Aseroidea Sea stars Ophiuroidea Brittle stars Echinoidea Sea urchins and sand dollars Holothuroidea Sea cucumbers

42. Phylum Annelida

43. Phylum Cnidaria

44. Phylum Mollusca

45. Phylum Echinodermata

46. Phylum Arthropoda

47. Phylum Nematoda

48. Phylum Platyhelminthes

49. Phylum Porifera

50. ... the exoskeleton

51. ... none

52. ... segmentation

53. ... it is one way; having both a mouth and an anus

54. ... bilateral symmetry and cephalization

55. ... radial symmetry

56. ... the coelom

79. An open circulatory system limits the size of these animals

80. The closed circulatory system is much more efficient!