Annelida

1. Annelida Segmented Worms

2. N0- not that kind of worm!

3. Common Examples • Earthworms

4. Common Examples • Bristle Worms

5. Common Examples • Feather Duster Worms

6. Common Examples • Tube Worms

7. Common Examples • Tube Worms

8. Common Examples • Leeches

9. Rag Worm How would you like to run into the jaws of this guy!

11. Characteristics • Segmentation • Cephalization • Bilateral Symmetry • Coelomates • One way digestive tract • Both Filter Feeders and Predators • Asexual and Sexual Reproduction • Water and Land Examples

12. Segmentation • Each segment repeats • Very efficient design. • Some are specialized • Digestion, reproduction,excretion, etc.

13. Definite Head End

14. Annelida has Bilateral Symmetry Yes, Symmetric No, not Symmetric No, not Symmetric

15. Body Structure Section 27.2 Summary – pages 728-733 • The basic body plan = a tube within a tube • internal tube= suspended w/in coelom = digestive tract.

16. Phylum Annelida Hydrostatic skeleton Fluid pressure in coelom provides support & locomotion Circular muscles Longitudinal muscles Peristaltic locomotion – squeeze, relax, squeeze!

17. Body Structure Section 27.2 Summary – pages 728-733 • SETAE = tiny bristles on each segment • help move • anchors body in soil so each segment can move the animal along Setae

18. Phylum Annelida Setae (“bristles”) of chitin – a carbohydrate Chitin forms the exoskeleton in insects, shrimp, crayfish, etc. “anchors” for earthworm “paddles” for polychaete Enlarged as jaws in leeches, some polychaetes

19. Body Structure Section 27.2 Summary – pages 728-733 • distinguishing characteristic is that bodies are divided into ringed segments • In most species, segmentation continues internally as each segment is separated from the others by a body partition. Segments

20. Body Structure Section 27.2 Summary – pages 728-733 • Each segment has its own muscles, allowing shortening and lengthening of the body. • Segmentation also allows for specialization of body tissues. • Certain segments have modifications for functions such as sensing and reproduction.

21. Section 27.2 Summary – pages 728-733 Nervous system • Segmented worms have simple nervous systems in which organs in anterior segments have become modified for sensing the environment = cephalization • Some sensory organs are sensitive to light, and eyes with lenses and retinas have evolved in certain species.

22. Nervous system • In some species there is a brain located in an anterior segment. Setae • Nerve cords connect the brain to nerve centers called ganglia, located in each segment. Brain

23. Phylum Annelida Closed circulatory system Multiple “hearts” Hemoglobin not in blood cells reddish-pink color Blood carries O2 to and CO2 from body cells flow through vessels to reach all parts of the body must live in water or in wet areas on land because they exchange gases directly through their moist skin – like your lungs

24. Digestion and Excretion Section 27.2 Summary – pages 728-733 • complete internal digestive tract • length of body • Nutrients diffuse to blood • Transported to all cells • Food > mouth > crop >gizzard > gut >anus

25. Digestion and Excretion Section 27.2 Summary – pages 728-733 Gizzard Crop • GIZZARD • a muscular sac • Contains hard particles to grind soil and food before they pass into intestine/gut Mouth Circulatory System

26. Excretion Section 27.2 Summary – pages 728-733 • have two nephridia in almost every segment. • Special cells that collect waste and transport it through the coelom and out of the body. Nephridia

27. Reproduction Section 27.2 Summary – pages 728-733 • Earthworms and leeches are hermaphroditic • exchange sperm. • forms a capsule for the eggs and sperm. • The eggs fertilized in capsule, then it slips off the worm and left in soil • 2-3 weeks, young worms emerge from the eggs.

28. Reproduction in Bristleworms • separate sexes and reproduce sexually. Section 27.2 Summary – pages 728-733 • eggs and sperm are released into seawater and fertilize there = external fertilizaton • larvae hatch in sea • become part of the plankton –important part of food chain • Eventually settles to the bottom to live

29. CLASSES OF ANNELIDA Section 27.2 Summary – pages 728-733 • ClassOligochaeta - earthworms • Class Polychaeta - bristleworms • Class Hirudinea - leeches

30. Class Oligochaeta: Earthworms Section 27.2 Summary – pages 728-733 • most well-known annelids • Easily seen by most people. • burrows through soil • Loosens and aerates soil • Feces = “castings” = fertilizer • Ecologically very important • Possible human food source= protein

31. Class Polychaeta:Bristleworms Section 27.2 Summary – pages 728-733 • Polychaete means “many bristles” • Most body segments have many setae • has a head with well-developed sense organs, including eyes.

32. Class Polychaeta:Bristleworms Section 27.2 Summary – pages 728-733 • have parapodia, (paired feet) • can be used for swimming or crawling over corals and bottom of sea. • Parapodia also function in gas exchange.

33. Class Hirudinea: Leeches Section 27.2 Summary – pages 728-733 • segmented worms with flattened bodies • usually no setae • Many are parasites • suck blood or other body fluids from hosts (ducks, turtles, fish, and humans).

34. Hirudinea: Leeches Section 27.2 Summary – pages 728-733 • Front and rear suckers for attachment • saliva contains: • anesthetic chemicals • Anticoagulants – prevent clotting of blood • can ingest 2 to 5 times its weight in 1 meal.

35. Origins of Segmented Worms • Annelids probably evolved in the sea, perhaps from larvae of ancestral flatworms. Section 27.2 Summary – pages 728-733 • Tubes constructed by polychaetes are the most common fossils of this phylum. • Some of these tubes appear in the fossil record as early as 540 million years ago.