phylum annelida

1. Phylum Annelida Chapter 13

3. Samoan Palolo worm

4. Samoan Palolo worm

5. Just show the first 2:45 minutes once the manta rays are shown stop!!!!!!!Just show the first 2:45 minutes once the manta rays are shown stop!!!!!!!

6. Phylum Annelida Class Polychaeta Marine worms Class Clitellata Subclass Oligochaeta- Soiling building worms Subclass Hirudinea- Predatory leeches

7. Phylum Annelida Characteristics Metamerism - segmented body Bilateral Protostome Wormlike Epidermal Setae Closed Circulatory System Dorsal ganglia and ventral nerve cord Metanephridia or protonephridia

8. Metamerism and Tagmatization Metamerism � segmentation of body parts. Each segment has: excretory, nervous, and circulatory structures

9. Advantages of Metamerism: 1. Hydrostatic compartments- allows variety of locomotor and supportive functions like swimming, crawling, and burrowing.

10. Advantages of Metamerism: 2. Lessens the impact of injury- if few segments injured others can perform normal functions which increases the likelihood that the worm will survive.

11. Advantages of Metamerism: 3. Tagmatization- permits the modification of certain regions of the body for specialized functions like feeding, locomotion, and reproduction.

12. Advantages of Metamerism:

13. Advantages of Metamerism:

14. Class Polychaeta

15. Class Polychaeta Characteristics Marine 5 � 10 cm in length 5,300 species Largest of the annelid classes

16. Class Polychaeta Live: On the ocean floor Under rocks and shells Within crevices of coral reefs Some can burrow

17. External Structure and Locomotion Parapodia � lateral extensions supported by chitin Setae � bristles secreted from the distal ends of the parapodia Important for locomotion/ digging

18. Parapodium

19. Parapodia and Setae

20. Parapodia and Setae See them work in action

21. External Structure and Locomotion Prostomium- lobe that projects dorsally and anterior to mouth contains: eyes, antennae, palps and nuchal organs Nuchal organs: ciliated sensory pits which are chemoreceptors for food detection

22. External Structure and Locomotion Peristomium- first body segment; surrounds the mouth Annelids also secrete a nonliving cuticle from the epidermis for protection

23. Prostomium and Peristomium

24. Prostomium and Peristomium

26. Feeding and the Digestive System Digestive tract is a straight tube: Pharynx- when everted can form a proboscis (See it) Crop- storage sac Gizzard- grinding Intestine-long and straight The video shows a Nemertean worm attacking a polycheata-you can see the polycheata proboscisThe video shows a Nemertean worm attacking a polycheata-you can see the polycheata proboscis

27. Feeding and the Digestive System Polychaeta can be: Predatory-usually burrow or live in coral crevices; some can have poison glands Herbivores Scavangers Filter feeders- tube dwelling (see them feed)

28. Examples of different worms and how they feed

29. Feeding and the Digestive System Elimination of waste for tube dwellers: If open ends: wastes carried away by water circulating in tube. If closed end: then the worms either turns around in tube OR uses ciliary tracts along body wall to carry feces out.

30. Feeding and the Digestive System Polychaetes that inhabit substrates rich in dissolved organic molecules can absorb as much as 20% to 40% of their food across their body walls (very unusual among animals)

31. Gas Exchange and Circulation Respiratory gases diffuse across body wall and parapodia (increase surface area) Closed circulatory system Oxygen is carried by molecules called respiratory pigments- blood colorless, green or red

32. Gas Exchange and Circulation Dosal aorta- propels blood from rear to front Ventral aorta- propels blood from front to rear With Capillaries between the two aortas

33. Nervous and Sensory A pair of Suprapharyngeal ganglia-controls motor and sensory functions; feeding and forward movement. Connects to A pair of Subpharyngeal ganglia- mediates locomotor functions required for coordination of distant segments. By Circumpharyngeal connectives-run dorsoventrally along the pharynx

34. Nervous and Sensory Ventral nerve cord with paired segmental ganglia in each segment; allows escape response of segments Segmental ganglia- coordinate swimming and crawling movements in isolated segments. 2�4 pairs of eyes

36. Excretion Excrete ammonia Most of the excretory organs in annelids are active in regulating water and ion balances Nephridia � excretory organs in annelids

37. Two types of Nephridia Protonephridia- tubule with a closed bulb at one end and a connection to the outside of the body at the other end. Metanephridia- open ciliated funnel (nephrostome) that projects through an anterior septum into the coelom of an adjacent segment

38. Excretion

39. Nephridia

41. Reproduction and Regeneration

42. Reproduction and Regeneration Most sexually reproduce Most are dioecious External fertilization and trochophore larvae Swarming occurs in some species, where large numbers of individuals join together to release sperm and/or eggs

43. Reproduction and Regeneration Very few species copulate (most external fertilization) A unique, weird, kinky copulatory habit has been reported in Platynereis megalops from Woods Hole, Massachusetts. Read page 216 for the details. . .

44. Reproduction and Regeneration Epitoky- formation of a reproductive individual (an epitoke) that differs from the nonreproductive form of the species (an atoke). Epitoke- body modified into 2 body regions; anterior segments-normal maintenance; posterior segments-enlarged & filled with gametes Example: Samoan palolo worm swarm

45. In some species the epitoke breaks free from the atoke, which stays in the burrow

47. 3 Advantages of Swarming Epitokes 1. Nonreproductive individuals remain safe below the surface waters; predators cannot devastate an entire population.

48. 3 Advantages of Swarming Epitokes 2. External fertilization requires individuals to be ready at the same time. Swarming ensures large numbers of individuals are in the right place at the right time.

49. 3 Advantages of Swarming Epitokes 3. Swarming of vast numbers of individuals for brief periods provide a banquet for predators. But because it is such a BREIF period, predators can only eat so much with respect to the limits of their normal diets. Predators can dine gluttonously and still leave epitokes that will yield the next generation of animals.

50. Class Clitellata

51. Class Clitellata

52. Class Clitellata

53. Subclass Oligochaeta 3,000 species Freshwater and terrestrial habitats throughout the world (some marine) Aquatic species live in shallow water; burrow in mud and debris Terrestrial species live in soils with high organic content

54. So you want to see the biggest earthworm in the world? Go to Australia or sit back and watch this. . . Giant Gippsland Earthworm

55. External Features Have setae but fewer Lack parapodia- get in the way because of burrowing Prostomium- lacks sensory appendages

56. External Features Clitellum- secretes mucus during copulation and forms a cocoon (girdle-like structure)

58. Locomotion Have both circular and longitudinal muscles Move by antagonistic contractions of these muscles Bulging and elongating body segments in waves cause the worm to move forward Small setae help anchor the worm Small conical prostomium acts like a wedge while burrowing, and soil is swallowed (important for decomposition)

59. Feeding and Digestive System Scavengers-fallen and decaying vegetation Mouth->muscular pharynx->esophagus Esophagus expanded form of stomach, crop ( thin-walled storage structure), gizzard (muscular grinding structure). Calciferous glands-evaginations of esophagus wall that rids the body of excess calcium absorbed by food; regulates pH

60. Feeding and Digestive System Intestine-principle site of digestion and absorption Anus

61. Subclass Oligochaeta Gas Exchange and Circulation: same as polychaetes Nervous and Sensory: same as polychaetes but lack well-developed eyes

62. Excretion Oligochaetes use metanephridia for excretion of ammonia and urea and for ion and water regulation. Chloragogen tissue- acts like a liver for amino acid metabolism (deaminates amino acids into ammonia and urea); excess carbohydrates converts into glycogen and water

63. Reproduction

64. Reproduction

65. Figure 17.17

66. Reproduction Freshwater oligochaetes can reproduce asexually which is usually followed by the regeneration of missing segements.

67. Subclass Hirudinea 500 species Mostly freshwater but some marine and terrestrial Prey on small invertebrates or feed on the body fluids of vertebrates.

68. External Structures Lack parapodia and head appendages Leeches are dorsoventrally flattened and tapered anteriorly Anterior and posterior segments have suckers

69. External Structures Have 34 segments

70. Locomotion Have lost metameric partitioning, resulting in single body cavity Coelomic sinuses replace blood vessels in most leeches Complex musculature (four types of muscles) Move in looping motion or swim with undulations

71. Locomotion Inchworm-like crawling. Relatively few but large neurons. Extremely sensitive to temperature and vibration.

72. Feeding Feed on body fluids, blood of vertebrates, or entire bodies of invertebrates Ectoparasites

73. Feeding Mouth with sucker-3 chitinous jaws or proboscis

74. Feeding Have an anticoagulant and an anesthetic in saliva Anticoagulant: Hirudin- prevents blood from clotting

75. Feeding Pharynx-> esophagus-> large stomach with lateral cecea (increase body mass 2-10 times)-> short intestine-> anus

76. Figure 17.20

77. Subclass Hirudinea

78. Subclass Hirudinea