1. Chapter 13 Invertebrates Part II Mollusks, Worms, Arthropods & Echinoderms

2. Ch 13.1 - Mollusks A. Mollusks – soft bodied invertebrates with bilateral symmetry and usually 1 or 2 shells 1. Mantle – thin layer of tissue that covers organs and secretes shell 2. Mantle Cavity – b/w body and mantle; sometimes contains gills

3. 3. Open Circulatory System – blood moves in open spaces around organs 4. Sensory Organs – well developed head and mouth

4. 5. Foot – muscular underside of body used to move

5. 6. Radula – tongue-like organ with teeth used to get food

6. B. Mollusks are classified into 3 groups 1. Gastropods – have 0 or 1 shell a) Include snails, conchs and slugs

7. c) Glands in the foot secrete a layer of mucus for sliding

8. 2. Bivalves – have hinged 2 part shell a) Include clams, oysters and scallops

10. 3. Cephalopods – most complex mollusks; shell secreted internally a) Include squid, octopuses, cuttlefish and chambered nautiluses

11. Giant Squid

12. Octopus

13. Cuttlefish

14. Chambered Nautilus

15. b) Well developed head and many tentacles for capturing prey c) Closed Circulatory System – all blood in vessels d) Fossils date to more than 500 million years ago e) Jet Propulsion – move at 6 m/s Jet Propulsion Jet Propulsion

16. C. Uses of Mollusks 1. Food for people and other animals 2. Pearls and shells used for jewelry and decorations

17. Ch 13.2 – Segmented Worms A. Segmented worms – AKA annelids 1. Bilateral symmetry 2. Body cavity with organs 3. Two body openings (mouth & anus)

18. 4. Setae – bristle-like structures used to hold on to and move in the soil 5. Includes earthworms, marine worms and leeches

19. B. Earthworms - more than 100 segments 1. Move with 2 sets of muscles 2. Have closed circulatory system and small brain 3. Breath through mucus covered skin 4. Are hermaphrodites but must exchange sperm with another worm

20. 5. Digestive System a) Mouth – ingests soil b) Crop – food storage area c) Gizzard – grinds food d) Intestines – releases nutrients e) Anus – eliminates wastes which fertilizes soil

21. Earthworm Anatomy

22. C. Marine Worms – (AKA polychaetes) have segments with setae in bundles 1.Some are sessile and build tubes around their bodies for protection

24. 2. Some are free swimming

25. D. Leeches – segmented worms w/o setae that feed on blood of other animals

27. 1. Used in medicine to prevent blood from coagulating after surgery

29. 2. Chemicals released being studied as treatments for heart disease, strokes, arthritis and glaucoma

30. E. Uses of Segmented Worms 1. Aerate soil 2. Provide food for fish 3. Produce medically useful chemicals F. Seg. Worms probably evolved in the sea and had a common ancestor w/ mollusks

31. Ch 13.3 - Arthropods A. Characteristics 1. Jointed appendages 2. Bilateral symmetry 3. Most species have separate sexes 4. Some have body segments while others have fused areas called regions

32. 5. Exoskeletons – hard, thick outer covering that protects and supports a) Molting – process of shedding and replacing the exoskeleton

34. B. Insects 1. Have 3 body regions: a) Head – antennae, eyes & mouth b) Thorax – 6 legs & wings (if present) c) Abdomen – reproductive structures, open-circulatory sys. & respiratory sys. - contains pores for gas exchange called spiracles

36. 2. Undergo Metamorphosis – series of changes in body from birth to adult a) Incomplete Metamorphosis - egg, nymph, adult

38. b) Complete Metamorphosis - egg, larva, pupa, adult

41. 3. Eat plants, blood, nectar, wood, decaying materials, and cloth a) mouth parts are diverse and adapted to their diet

43. 4. Insects are successful due to: a) exoskeltons b) ability to fly c) rapid reproductive cycles d) small size

44. C. Arachnids 1. Have 2 body regions a) Cephalothorax – head & chest; b) Abdomen – reproductive structures 2. Includes spiders, scorpions, mites & ticks

45. a) Spiders – 8 legs & no antennae; cannot chew their food so they have venom glands that release enzymes to digest food into a liquid then suck it in

48. b) Scorpions – have sharp, poison-filled stinger at the end of their abdomen

49. c) Mites – many are plant and animal parasites but some are not such as ones that live in human eyelash follicles; look like tiny specs to human eye

50. d) Ticks – all are parasites that attach to host’s skin and suck blood; many carry disease

51. D. Centipedes & Millipedes 1. Have long bodies with many segments, many legs and antennae

52. E. Crustaceans 1. Have 1-2 pairs of antennae and mandibles for crushing food 2. Include crabs, lobsters, shrimp and barnacles

55. Ch 13.4 - Echinoderms A. Characteristics 1. Hard endoskeleton 2. Bumpy or spiny skin 3. Radial symmetry 4. Water vascular system to move and capture food

56. B. About 6,000 species exist 1. Sea Stars (starfish) – have 5 arms with bumpy skin around a central point; can regenerate a lost arm

57. 2. Brittle Stars – 5 skinny arms with spiny skin; can break arm off to escape predators

58. 3. Sea Urchins – globe shaped animal covered in spines

60. 4. Sand Dollars – disk shaped animal covered in spines

61. 5. Sea Biscuit

62. 6. Sea Cucumbers – soft, leathery bodied animal that resemble shape of cucumber