Phylum Annelida

1. Phylum Annelida the segmented worms

2. Activities and Assignments • Labs • Earthworm behavior (binder) • Earthworm Dissection (binder) • Video Med. Uses of Leeches (binder) • Quiz- short topic • Text Reading 671-674 • Worksheet • Vocabulary: monecious, dioecious, mutualism, tagmosis, detritus, triploblastic, coelom, septa, cerebral ganglia, parapodia, setae, parts of the worm anatomy from the lab

3. How do the Annelids fit in? Annelida Rotifera Nematoda Platyhelminthes Nemertea Cnidaria Porifera unknown common ancestor

4. Annelida Characteristics Triploblastic (3 tissue layers) Organ level of organization Bilateral Symmetry Cephalization Coelomate (with a body cavity)

5. Remember these ideas from the last chapter

6. Gut Coelomate Have a “true” body cavity that is completely surrounded by mesoderm ectoderm coelom mesoderm endoderm

7. Annelid Characteristics the coelom • is a closed, fluid filled cavity that surrounds the gut • the fluid within acts as a circulatory system and hydroskeleton • mesodermal membranes (mesenteries) suspend organs in the coelom ectoderm

8. Annelida Characteristics Metamerism • The body is made up of serially repeating, coordinated segments called metameres that are separated from one another by septa. • Each metamere contains sets of repeating organs • e.g. gut, blood vessels, nerve cord, excretory organs

9. Metamerism septa Think of a row of tires

10. Annelida Characteristics Nervous system • 2 cerebral ganglia • a ventral nerve cord with 2 ganglia per metamere. • In some species, sensory organs such as eyes, palps, and tentacles have arisen

11. brain nerve cord 2 cerebral ganglia

12. Annelida Characteristics Arthropod exoskeleton component Locomotion • fluid in coelom acts as a hydrostatic skeleton • both longitudinal and circular muscles • most have setae (chitonous bristles secreted by the epidermis) that aid in locomotion and burrowing Skeletal System

13. Class Oligochaeta Locomotion Circular muscle contraction Longitudinal muscle contraction

14. Annelind Cross section

15. Annelind Cross section Circular muscle Longitudinal muscle skin

16. Annelind Cross section coelom Circular muscle Gut (intestine) Longitudinal muscle Intestine wall skin

18. Annelid Characteristics Gas exchange • mainly by diffusion • Class Polychaeta often has specialized structures for gas exchange • (e.g. parapodia, gills)

19. Annelid Characteristics Digestive System You’ll get to observe these more closely during the dissection • complete • regional specialization Circulatory System • closed circulatory system composed of blood vessels (some of which are contractile and act as “hearts”) • some circulation is also accomplished by the coelomic fluid

20. coelomic chambers pharynx mouth esophagus crop (storage) gizzard (mashing) This diagram is found in the dissection lab

21. More properly called “aortic arches” One each on the dorsal and ventral sides hearts blood vessels

23. Annelid Characteristics Excretion • excretion is accomplished by organs called nephridia (singular nephridium) in the skin • sexual • Hermaphrodites (individuals with both sets of reproductive organs) Reproduction

25. Phylum Annelida Class Oligochaeta Class Hirudinea Class Polychaeta

26. Class Oligochaeta

27. Class Oligochaeta • terrestrial, freshwater and marine • have few setae (Oligo = few, chaeta = setae) • usually feed on detritus • (decaying organic matter) • have specialized digestive system to obtain the maximum amount of nutrients out of the detritus (e.g. pharynx, gizzard, crop…)

28. Class Oligochaeta Locomotion Circular muscle contraction Longitudinal muscle contraction

29. Class Oligochaeta Reproduction • usually monoecious • cross-fertilize by • exchanging sperm clitellum testis

30. Earthworms are essential soil aerators • If all the material ever moved through earthworms was piled up, the heap would rise 30miles , more than 5 times the height of Mount Everest!! • Worm Grunting: Ecology A saw or leaf spring of a pick-up stob

32. Class Hirudinea

33. Class Hirudinea • usually freshwater but there are some marine and terrestrial species • no septa between metameres • no setae • have 2 suckers

34. Class Hirudinea • have an extendable proboscis for feeding

35. Class Hirudinea • usually have a fixed number of segments (34) • each metamere consists of several annuli (think accordion) 1 metamere annuli

36. Locomotion Class Hirudinea Lack septa between metameres, so they are incapable of moving like Oligochaetes. Instead, they use their anterior and posterior suckers to move.

37. Reproduction • usually monoecious • cross-fertilize by • exchanging sperm Class Hirudinea

39. Although some leeches are parasitic blood suckers (can be temporary or permanent), many are predators. Ecology

40. video • Leeches have been used medicinally since the 19th century. • Currently they are used to increase blood flow following reconstructive surgery • Hirudin is a powerful anticoagulant that is found in the salivary glands of leeches • Leech saliva contains antiseptic chemicals • And an anesthetic Ecology DON’T WRITE THIS DOWN, YOU HAVE AN ARTICLE AND VIDEO WITH THE INFO

41. Class Polychaeta

42. all marine • this class contains 2/3 of all known Annelids • have a well developed head with specialized sense organs Class Polychaeta

43. have many setae (chitonous bristles secreted by the epidermis) • (Poly = many, chaeta= setae) • these setae are arranged in bundles on paddle-like appendages called parapodia Class Polychaeta setae

44. Parapodium Class Polychaeta setae The parapodia function in gas exchange, locomotion, and feeding.

45. Tagmatization (tagmosis) • the fusion and specialization of formerly metameric segments Class Polychaeta

46. Many are filter-feeders with specialized structures Class Polychaeta

47. Many are predatory with specialized structures Class Polychaeta

48. Class Polychaeta Many construct their own homes out of CaCO3 or sand debris and mucous

49. Polychaetes often have effective • defense strategies: • some have tubes to hide in • some have vicious jaws • some have modified “stinging” setae Ecology a fireworm