1. Unit 5.3 Phylum Annelida

2. MyxozoaMyxozoa ArthropodaArthropoda AnnelidaAnnelida MolluscaMollusca LophophoresLophophores HemichordataHemichordata VertebrataVertebrata OtherpseudocoelomatesOtherpseudocoelomates NematodaNematoda PoriferaPorifera CtenophoraCtenophora CnidariaCnidaria PlacozoaPlacozoa PlatyhelminthesPlatyhelminthes NemerteaNemertea CiliophoraCiliophora SarcomastigophoraSarcomastigophora MicrosporaMicrospora ApicomplexaApicomplexa MesozoaMesozoa EchinodermataEchinodermata CrustaceaCrustacea ChelicerataChelicerata UniramiaUniramia Other Chordata

3. 3 Phylum Annelida Segmented body –Each segment is called a metamere Each segment contains tiny hairs called setae that are used for various purposes –Absent in leeches Coelom (internal body cavity) is divided by septa

4. Phylum Annelida Annelids were the first organisms to develop a closed circulatory system Several one- chambered hearts connect vessels on either side of the esophagus and flex via peristalsis as the worm moves

5. Septa Prostomium Pygidium Phylum Annelida Annelid bodies are divided by septa into repeating segments. Each segment contains their own set of excretory organs called nephridiopores. This attribute is called Metamerism

6. Annelid larva Apical tuft MouthMouth AnusAnus Ciliary band StomachStomach

7. Annelid development

8. 8 Class Polychaeta Generally marine Each body segment has a pair of fleshy protrusions called parapodia Parapodia function in locomotion as well as in respiration (think external gills) Well developed heads compared to other annelids

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10. Class Polychaeta Head Parapodium Tentacle

11. Class Polychaeta Predatory JawJaw Everted pharynx EyeEye CirrusCirrus PalpPalp TentacleTentacle ParapodiumParapodium

12. Class Polychaeta

13. Epitoky – a transformation into the breeding form of an organism Epitokes are given the task of reproduction Some species bud epitokes from the body and remain in their habitat while the epitokes move to the surface to breed

14. Class Polychaeta Dioecious Many species reproduce en masse at the water’s surface at night Moonlight and artificial light attract spawning masses The Palolo worm is harvested in Samoa and eaten as a delicacy

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16. Tube-Dwelling Polychaetes Tubeworms & Featherdusters Defining characteristic –Gut tissue forms an organ (trophosome) that becomes filled with chemosynthetic bacteria –Segmentation confined to small rear portion of animal Small intriguing class of tube dwelling worms found throughout the worlds oceans

17. Tube-Dwelling Polychaetes The most interesting aspect of tube worms is the lack of a digestive system –Bacteria in the trophosome fix the chemicals leaving the vents –The bacteria can occur at concentrations of 10 billion per gram of trophosome tissue

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19. Burrowing Polychaetes Lugworms Castings can be seen on the beach at low tide Lives in a U-shaped burrow in the sand Eat sand, extract biological material from the rock, and then expel the castings outside of the burrow

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22. Free-living Polychaetes Common sandworms and fireworms Use parapodia like little legs for locomotion Roam the ocean floors searching for food Fireworm setae contain potent neurotoxins and can cause a painful rash if touched 22

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24. Class Oligochaeta Earthworms Few setae – very hard to see hairs compared with polychaetes Clitellum – barrel shaped sexual structures near the anterior end of the worm No parapodia Monoecious

25. Class Oligochaeta Extremely important ecologically Biological – breaks down organic matter leaving rich, dark soil Chemical – frees phosphates for use in plants Physical – aerates the soil by digging tunnels that allow air and water to penetrate

26. 26 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. External Structures of an Earthworm

28. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Internal Structures of an Earthworm

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31. Class Oligochaeta Copulation & fertilization are separate Copulation – two earthworms line up with their anterior ends facing each other and exchange sperm

32. Class Oligochaeta Fertilization –after the worms exchange sperm, the clitellum turns bright pink and secretes a chitinous cocoon around the worm The worm then wriggles out of the cocoon and deposits its eggs and its partner’s sperm into the cocoon allowing fertilization to take place Worms hatch as small adults – no larval stage

33. Earthworm Reproduction Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

34. Class Hirudinea Leeches Anterior & posterior suckers Predominately freshwater, but do occur in all seas and moist soil Leeches do not burrow or crawl, they lack parapodia and setae – instead they move like an inchworm

35. Class Hirudinea Anterior sucker is small and contains the mouth –Anterior sucker creates a wound with saw like jaws Leeches drink other animals’ blood, usually vertebrates –Can be carnivores, or scavengers; leeches are not set in their feeding habits Leech saliva contains an anticoagulant that numbs the wound and keeps the blood flowing

36. Class Hirudinea Leeches are simultaneous hermaphrodites that lack a free-living larvae stage Fertilization is internal through copulation Development occurs in a cocoon similar to the Oligochaetes

38. The End