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23 Cards in this Set
- Front
- Back
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Major evolutionary milestones
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-Coelum (true gut)
-Closed circulatory system |
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Characteristics
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- segmented bodies
- bilateral symmetry - true body cavity sep. by septa -organs of 3 systems penetrate septa and run length of body - one way digestive tract divided into sev well dev. organs: pharynx, esphagous, crop, gizzard, intestine |
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Circulatory system
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-closed (first time ever seen)
-contains dorsal + ventral blood vessel: connected by 5 aortic arches above esophagus |
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Dorsal blood vessel
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carries blood from tail to head
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ventral blood vessel
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carries blood back toward tail
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Cephalization
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-Brain: small, located under pharynx
-Ventral nerve cord extends from brain and runs length of body -each segment swells to form ganglion |
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Ganglion
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nerve cell cluster (site for transferring info)
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Excretion
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-nitrogenous waste removed from body by nephridia
-each segment = 2 nephridia |
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Nephridia
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-removes nitrogenous waste from body
-each body segment contains 2 (except for first 3 and last one) |
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Reproduction
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-hermaphroditic
-internal fertilization via copulation -clitellum |
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Clitellum
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swollen segment on body that contains gland cell that produces cocoon to surround eggs after laid to protect them as they develop
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Locomotion
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-muscular system contains both circular/longitudinal muscles
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circular muscles
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contract to elongate body
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longitudinal muscles
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shorten body
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setae
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small, bristle-like hairs: extend from body walls + act like anchors as worm moves.
-4 setae per segment |
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Skin
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-contains then waterproof layer called cuticle
-no respiratory organs: breathe through moist skin |
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cuticle
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thin, waterproof layer
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body
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no skeleton other than hydrostatic one formed by fluid filled body cavity
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Classes of phylum annelida
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-Oligochaeta
-Polychaeta -Hirudinea |
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Class Oliogchaeta
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-"few bristles"
-the earthworms |
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Class Polychaeta
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-"many bristles"
-marine worms -have fleshy projections called "parapodia" to help them move + for gas exchange |
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Hirudinea
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-leeches, freshwater
-75% blood-sucking parasites that attach to host + release chemical "hirudin" that stops blood from clotting -slow digestion, can go 1 year bw meals |
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Ecological roles
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-mix + aerate soil
-decompose dead organic matter -fertilize soil by excreting waste |
