BIOL 101 Lecture Notes - Lecture 10: Parapodium, Leech, Hydrostatic Skeleton
Document Summary
Allows for more precise control of movement. Each segment separated by membrane (septum: setae (synapomorphy of annelida): Paired appendages called parapodia (arms where setae project from) Moves down the body to the sperm duct where sperm from another individual has been stored. Clitellum falls off and turns into cocoon. 500 species, most freshwater, few moist terrestrial. Clitellum present: only appears when ready to reproduce. Cut can store large amount of blood. Release anticoagulant in their saliva (prevents blood from clotting) When attaching limbs, used to reduce blood pressure. Non-chitinous exoskeleton (ancestral condition): secrete a non- cellular cuticle of collagen. 12,000 species described (but there are many more), extremely numerous and diverse, an acre of soil can contain a billion nematodes. Symbiotic mutualism: live in large intestines of iguanas to help digest plant material digest plant material. If ingested, eggs hatch and penetrate intestinal wall. Similar to intestinal roundworms, but enter through skin. Adults hook into intestinal wall sucking blood.
