BIOL 202 Study Guide - Midterm Guide: Cephalopod, Endoskeleton, Hectocotylus
12 Jan 2016
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Hydraulic skeleton as well as coiled shell (exoskeleton) Pedal locomotion also by larger gastropods (waves across body. Primitive, have 6 ganglia located in head/foot of visceral mass. Evolution of gastropods resulted in untwisting of nerves and concentration of nervous tissues into fewer, larger ganglia, especially in the head: eyes at base or end of tentacles, may be simple or have lens and. Chemoreceptor: osphradia in anterior wall of mantle cavity, may help detect prey. Gills: primitive had two, lost one because of coiling. Open circulatory system: heart consisting of a single, muscular ventricle and two auricles (lost one auricle because of coiling) Scrape algae or small attached organisms from substrate using radula herbivores, scavengers, parasites, or predators. Some dioecious, gonads lie in spirals of visceral mass and ducts discharge gamete into sea for external fertilization. Others are monoecious and use internal cross-fertilization. Foot is bladelike (laterally compressed) and pointed for digging (muscular movement)
