BIOL 2P92 Lecture Notes - Lecture 19: Anticoagulant, Nephridium, Seta
19 Feb 2016
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Document Summary
Few are marine and some even adapted to terrestrial life (moist, warm areas) 2 and 6cm some smaller, some reach 20cm + Members of a clade sometimes called true leeches have 34 segments. Coleom filled with connective tissue and muscle reducing effect of hydrstatic skeleton. Most have muscular, protrusible proboscis or muscular pharynx with 3 jaws armed with teeth. Blood sucking leeches secrete anticoagulant in saliva. Predatory leeches feed frequently, those that feed on the blood of vertebrates consume large meals, digest slowly. Depend on bacteria in gut to digest blood meal. Have clitellum, evident only during breeding season. Head forms an introvert, crowned by ciliated tentacles surrounding mouth. Deposit feeders, extendin introvert and tentacles from burrow to explore & Have cerebral ganglion, nerve cord, and pair of nephridia. U-shaped gut lying within a spacious coelom. Coelomic fluid contains red blood cells bearing a respiratory pigment called feed hemerythrin.
