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Annelida: Segmented W orms

Annelida: Segmented W orms. By Allison Letcher. Key Characteristics. Have a complete gut (true coelom) Segmented externally and internally Bilaterally symmetrical Has more then 2 cell layers Has muscles that go longitude and circular layers. Anatomy. Mouth Pharynx

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Annelida: Segmented W orms

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  1. Annelida: Segmented Worms By Allison Letcher

  2. Key Characteristics • Have a complete gut (true coelom) • Segmented externally and internally • Bilaterally symmetrical • Has more then 2 cell layers • Has muscles that go longitude and circular layers

  3. Anatomy • Mouth • Pharynx • Helps mouth draw in organic mater • Esophagus • Crop • Food is stored • Gizzard • Muscular walls lined with protective cuticle, gridding structures • Intestines • Further digestion and absorption occur • Ventral nerve cord • Connects segments to cerebral ganglion • Anus • Clitellum • Glandular ring, secretes mucous • Dorsal/ventral blood vessels • Transmits blood

  4. Digestion • One way digestion • Mouth • Esophagus/pharynx • Crop • Gizzard • Intestines • Anus • Un-segmented gut that runs entire length of body • starting at mouth and ending at the anus • Squeeze organic material out of the earth

  5. Respiration • No special organs used for respiration • Occurs directly through body wall • Marine annelids have gills in most of the segments • Gives off carbon dioxide • Always moist skin allows oxygen in easier

  6. Internal Transport • Closed circulatory system • Confined in well developed blood vessels • Distributed to body compartments by lateral vessels • Lateral vessels act as hearts • Blood flows through contractile vessels to terminal region • 5 aortic arches that pump blood through the body

  7. Excretion • Starts at organ called metanephridia • Funnel like organ in middle of body cavity collects waste • Connected to a duct that carries waste to nephrostones • Attached to septum dividing two segments at anterior segment • Leaves through a pore in the body called nephridipore

  8. Response • Consists of primitive brain • connected by ring of nerves to the ventral nerve cord that runs length of body • Cord provides lateral nerves in each segment • Sense organs include • Eyes, taste buds, tactile tentacles • consists of nerve cords that run along the the entire length of the body

  9. Movement • Use setae and parapodia • Extends body, Anchors to a surface with setae, contracts body muscles • Forward Movement • Anterior circular muscles contract (extends head forward) • Anterior end lifts from the surface • Facilitate forward movement.

  10. Reproduction • Sexual or asexual • Asexual • Fragmentation, budding or fission • Sexually • Hermaphrodites are common as well as separate sexes • Marine annelids • Fertilized eggs of marine annelids develop into free-swimming larvae • Terrestrial forms • enclosed in cocoons and hatch as miniature version of adults

  11. Examples Sandworms Earthworms Leeches Rag worms

  12. Facts • 17,000 different species • Earthworms 7-35 cm in length • 700 different species of leeches • 500 species of rag worms (mostly marine) • First to have a true coelom

  13. Literature Cited • http://annelidsh.blogspot.com/2007/03/general-anatomy.html • http://www.infoplease.com/encyclopedia/science/annelida-annelid-characteristics.html • http://fairfun.net/my2/fauna_my/fauna_my-pisces/Pisces/0Paisley%20Fish%20Taxonomy/units/anne6.htm • http://www.britannica.com/EBchecked/topic/26308/annelid/31776/Locomotion • http://excreting101.weebly.com/annelida.html • http://www.esu.edu/~milewski/intro_biol_two/lab__12_annel_arthro/Annelida.html • http://rspp.weebly.com/annelid.html

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