1. Animal Characteristics Heterotrophs –must ingest others for nutrients Multicellular –complex bodies No cell walls –allows active movement Sexual reproduction –no alternation of generations –no haploid gametophyte

3. Porifera Cnidaria Platyhelminthes spongesjellyfishflatworms roundworms Nematoda MolluscaArthropodaChordata AnnelidaEchinodermata mollusks multicellularity Ancestral Protist tissues bilateral symmetry body cavity segmentation Animal Evolution coelom starfishvertebrates endoskeleton segmented worms insects spiders backbone specialization &  body complexity specialized structure & function, muscle & nerve tissue distinct body plan; cephalization  body complexity  digestive & repro sys  digestive sys  body size redundancy, specialization,  mobility  body & brain size,  mobility radial bilateral

4. Body Cavity ectoderm mesoderm endoderm ectoderm mesoderm endoderm mesoderm endoderm acoelomate pseudocoelomate coelomate coelom cavity pseudocoel Space for organ system development –increase digestive & reproductive systems increase food capacity & digestion increase gamete production Coelem –mesoderm & endoderm interact during development –allows complex structures to develop in digestive system ex. stomach protostome vs. deuterostome

5. The basic organization of germ layers differs between radiata and bilateria. The radiata are said to be diploblastic because they have two germ layers. –The ectoderm, covering the surface of the embryo, give rise to the outer covering and, in some phyla, the central nervous system. –The endoderm, the innermost layer, lines the developing digestive tube, or archenteron, and gives rise to the lining of the digestive tract and the organs derived from it, such as the liver and lungs of vertebrates. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings

6. The bilateria are triploblastic. –The third germ layer, the mesoderm lies between the endoderm and ectoderm. –The mesoderm develops into the muscles and most other organs between the digestive tube and the outer covering of the animal. Copyright © 2002 Pearson Education, Inc., publishing as Benjamin Cummings The Bilateria can be divided by the presence or absence of a body cavity (a fluid-filled space separating the digestive tract from the outer body wall)

8. Porifera Cnidaria Platyhelminthes spongesjellyfishflatworms roundworms Nematoda MolluscaArthropodaChordata AnnelidaEchinodermata mollusks multicellularity Ancestral Protist tissues bilateral symmetry body cavity segmentation Animal Evolution coelom starfishvertebrates endoskeleton segmented worms insects spiders backbone specialization &  body complexity specialized structure & function, muscle & nerve tissue distinct body plan; cephalization  body complexity  digestive & repro sys  digestive sys  body size redundancy, specialization,  mobility  body & brain size,  mobility radial bilateral

9. Invertebrate: Platyhelminthes ectoderm mesoderm endoderm Flatworms –tapeworm, planaria –mostly parasitic –bilaterally symmetrical have right & left & then have head (anterior) end & posterior end –cephalization = development of brain –concentration of sense organs in head increase specialization in body plan Animals now face the world head on! acoelomate

10. Flatworms Members of phylum Platyhelminthes live in marine, freshwater, and damp terrestrial habitats Although flatworms undergo triploblastic development, they are acoelomates They are flattened dorsoventrally and have a gastrovascular cavity Gas exchange takes place across the surface, and protonephridia regulate the osmotic balance

11. Flatworms are divided into four classes: –Turbellaria (mostly free-living flatworms) –Monogenea (monogeneans) –Trematoda (trematodes, or flukes) –Cestoda (tapeworms)

12. Table 33-2

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

14. Fig. 33-9

15. Planarians have light-sensitive eyespots and centralized nerve nets The planarian nervous system is more complex and centralized than the nerve nets of cnidarians Planarians are hermaphrodites and can reproduce sexually, or asexually through fission

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

17. 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 with alternating sexual and asexual stages Trematodes that parasitize humans spend part of their lives in snail hosts Most monogeneans are parasites of fish

18. Fig. 33-11 Human host Motile larva Snail host Ciliated larva Male Female 1 mm

19. 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

20. Proglottids with reproductive structures Hooks Sucker Scolex 200 µm Scolex Proglotid

22. Invertebrate: Nematoda Roundworms –bilaterally symmetrical –body cavity pseudocoelom = simple body cavity digestive system –tube running through length of body (mouth to anus) –many are parasitic hookworm C. elegans

23. Nematodes Nematodes, or roundworms, are found in most aquatic habitats, in the soil, in moist tissues of plants, and in body fluids and tissues of animals They have an alimentary canal, but lack a circulatory system Reproduction in nematodes is usually sexual, by internal fertilization

24. Fig. 33-25 25 µm

25. Some species of nematodes are important parasites of plants and animals Encysted juveniles Muscle tissue 50 µm

29. Guinea worms Guinea worm infections (also referred to as Dracunculiasis) are now confined to sub- Saharan Africa. Adults are threadlike nematode worms that can grow to 1 meter in length. The adult lives in humans and the intermediate host is tiny crustaceans. Humans become infected when they drink water containing the crustaceans.

30. Guinea worms The immature worm penetrates the gut wall and wanders through the body, maturing and growing. After about a year the female makes her way to the surface of the skin (usually in the legs) causing very painful blistering.

31. Guinea worms To ease the pain, sufferers immerse their feet in water. This bursts the blisters and the female worm then protrudes from the sore and lays her eggs, thus continuing the life cycle.

32. Guinea worms There is no cure for Guinea worms and the only way to remove one is to slowly over the course of weeks wind the worm out on a stick. If the worm breaks, a serious bacterial infection results.

34. Ascaris lumbricoides

35. Invertebrate: Mollusca Mollusks –slugs, snails, clams, squid –bilaterally symmetrical (with exceptions) –soft bodies, mostly protected by hard shells –true coelem increases complexity & specialization of internal organs

36. 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

37. All molluscs have a similar body plan with three main parts: –Muscular foot –Visceral mass –Mantle Many molluscs also have a water-filled mantle cavity, and feed using a rasplike radula

38. Fig. 33-15 Nephridium Visceral mass Coelom Mantle cavity Heart Intestine Gonads Stomach Shell Radula Mouth Esophagus Nerve cords Foot Gill Anus Mouth Radula

39. 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

40. There are four major classes of molluscs: –Polyplacophora (chitons) –Gastropoda (snails and slugs) –Bivalvia (clams, oysters, and other bivalves) –Cephalopoda (squids, octopuses, cuttlefish, and chambered nautiluses)

41. Table 33-3

42. Fig. 33-16

43. Fig. 33-17 (a) A land snail (b) A sea slug

44. Most gastropods are marine, but many are freshwater and terrestrial species Most have a single, spiraled shell Slugs lack a shell or have a reduced shell The most distinctive characteristic of gastropods is torsion, which causes the animal’s anus and mantle to end up above its head

45. Fig. 33-18 Mouth Anus Mantle cavity Stomach Intestine

46. Fig. 33-20 Mouth Digestive gland Mantle Hinge area Gut Coelom HeartAdductor muscle Anus Excurrent siphon Water flow Incurrent siphon Gill Gonad Mantle cavity Foot Palp Shell

47. Fig. 33-21 Octopus Squid Chambered nautilus

48. Cephalopods have a closed circulatory system, well-developed sense organs, and a complex brain Shelled cephalopods called ammonites were common but went extinct at the end of the Cretaceous

49. Invertebrate: Annelida Segmented worms –earthworms, leeches –segments increase mobility redundancy in body sections –bilaterally symmetrical –true coelem fan wormleech

50. Annelids Annelids have bodies composed of a series of fused rings The phylum Annelida is divided into three classes: –Oligochaeta (earthworms and their relatives) –Polychaeta (polychaetes) –Hirudinea (leeches)

51. Table 33-4

52. Oligochaetes Oligochaetes (class Oligochaeta) are named for relatively sparse chaetae, bristles made of chitin They include the earthworms and a variety of aquatic species Earthworms eat through soil, extracting nutrients as the soil moves through the alimentary canal Earthworms are hermaphrodites but cross-fertilize

53. Fig. 33-22 Epidermis Circular muscle Longitudinal muscle Dorsal vessel Chaetae Intestine Nephrostome Fused nerve cords Ventral vessel Metanephridium Septum (partition between segments) Coelom Cuticle Anus Metanephridium Crop Intestine Gizzard Ventral nerve cord with segmental ganglia Blood vessels Subpharyngeal ganglion Mouth Cerebral ganglia Pharynx Esophagus Clitellum Giant Australian earthworm

54. Polychaetes Members of class Polychaetes have paddle-like parapodia that work as gills and aid in locomotion Parapodia

55. Leeches Members of class Hirudinea are blood-sucking parasites, such as leeches Leeches secrete a chemical called hirudin to prevent blood from coagulating

56. Invertebrate: Arthropoda Spiders, insects, crustaceans –most successful animal phylum –bilaterally symmetrical –segmented specialized segments allows jointed appendages –exoskeleton chitin + protein

57. Arthropod groups insects 6 legs, 3 body parts crustaceans gills, 2 pairs antennae crab, lobster, barnacles, shrmp arachnids 8 legs, 2 body parts spiders, ticks, scorpions

58. Fig. 33-37a

59. Fig. 33-37b

60. Fig. 33-37c

61. Fig. 33-37d

62. Fig. 33-37e

63. Invertebrate: Echinodermata Starfish, sea urchins, sea cucumber –radially symmetrical as adults –spiny endoskeleton –deuterostome loss of bilateral symmetry?

64. Invertebrate quick check… Which group includes snails, clams, and squid? Which group is the sponges? Which are the flatworms? …segmented worms? …roundworms? Which group has jointed appendages & an exoskeleton? Which two groups have radial symmetry? What is the adaptive advantage of bilateral symmetry? Which group has no symmetry? Invertebrates: Porifera, Cnidaria, Platyhelminthes, Nematoda, Annelida, Mollusca, Arthropoda, Echinodermata