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Annelida. http://surferjerry.com/wp-content/uploads/2009/02/giant-south-african-earthworm.png. Segmented worms. By Emily Chu and Wonhyoung Kim. Classes. Oligochaeta (earthworms and relatives) Polychaeta (polychaetes) Hirudinea (leeches). Leech. Earthworm. Christmas tree worm.
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Annelida http://surferjerry.com/wp-content/uploads/2009/02/giant-south-african-earthworm.png Segmented worms By Emily Chu and Wonhyoung Kim
Classes • Oligochaeta (earthworms and relatives) • Polychaeta (polychaetes) • Hirudinea (leeches) Leech Earthworm Christmas tree worm http://www.cheshirewildlifetrust.co.uk/IMAGES/watch_earthworm.jpg http://www.microteufel.com/TripReports/Maui/Aquarium/IMG_0063s.jpg http://www.io.com/~dierdorf/leech.jpg
Body Cavity (coelom) • Present • Annelida=coelomate (has a true coelom) http://biology.unm.edu/ccouncil/Biology_203/Images/SimpleAnimals/Coelomate.JPG
Body symmetry • Bilateral symmetry
Nervous system • Have brain-like pair of cerebral ganglia • Ventral nerve cords with segmental ganglia (runs through length of body)
Circulatory system • Closed circulatory system—blood contained within vessels • Blood contains oxygen-carrying hemoglobin
Digestive System • Earthworms eat through the soil, extracting nutrients as the soil passes through the alimentary canal. • Have digestive tract http://johnson.emcs.net/life/images/earthworm.jpg
Excretory system • Metanephridium=excretory tubes • Remove waste from the blood and coelomic fluid through exterior pores • Nephrostomes=ciliated funnels
Locomotion/musculature • Chaetae=bristles that provide traction for burrowing • Each segment is surrounded by a longitudinal muscle, which is in turn surrounded by circular muscle. • Contractions of these muscles allow for movement. http://oceanexplorer.noaa.gov/explorations/03windows/logs/jul28/media/naut_allseate_600.jpg
Skeletal type • No true skeleton • Hydrostatic skeleton—controlled by coelomic fluid
Sensory structures/features • Simple sensory structures • Single-celled structures detect light, chemicals, pressure waves, and contact • Some polychaetes have ocelli (“little eyes”)
Reproduction • Hermaphrodites • Earthworms cross-fertilize • Two earthworms exchange sperm then separate • Received sperm are stored temporarily while the clitellum secretes a mucous cocoon • Cocoon slides along the worm, picking up eggs and then the stored sperm • Some earthworms can also reproduce asexually by fragmentation followed by regeneration
Clitellum http://static.howstuffworks.com/gif/willow/earthworm-info0.gif
Gas exchange • SKIN! This is the respiratory organ. • Hemoglobin in blood carries oxygen • Some polychaetes have gills http://upload.wikimedia.org/wikipedia/commons/e/ea/Christmas_tree_worms.jpg
Other Unique features • Today, leeches are used to drain blood that accumulate in tissues following certain injuries. • Leeches secrete hirudin (prevents blood from clotting, which allows leech to feed) • Hirudin has the potential to be used in the future to dissolve blood clots that form during surgery or as a result of heart disease.
Just kidding… http://www.breaktaker.com/albums/pictures/animals/LaughingCat.jpg
QUIZ TIME! • What is the primary respiratory organ? • Describe the annelid’s circulatory system. • Give two examples of methods of reproduction and explain each. • Which of these phyla consists of species with a coelom? • Porifera • Cnidaria • Annelida • Platyhelminthes
Check your answers! • The skin • Closed circulatory system • Sexual—two hermaphroditic annelids align and exchange spermclitellum secretes cocoon Asexual—fragmentation and regeneration • C. Annelida