BIOL 101 Lecture Notes - Lecture 9: External Fertilization, Veliger, Arthropod
Document Summary
Most are small, under 5cm, some large, over 40 ft. Mollusca is the second most diverse group behind arthropoda. Found on ocean bottom, some at 6,000 meters. Trap food with cilia of foot and tentacles. Gills modified for filter feeding (loss of use of mouth and loss of radula) Sedentary suspension feeders using mucus on gills. Uses siphons to move water in and out (incurrent and excurrent) Produces sheets of mucus on gills that trap the food found in water. Ciliated cells on gills move the mucus to the stomach where it is digested. Foot can be extended and retracted, used to anchor animal and burrow. Torsion: process of twisting of internal organs in order to fit in spiraled shell, anus ends up near middle of body. Gills lost in terrestrial species, mantle cavity becomes a lung (pulmonates: snails that live on land) Process nematocysts and transfer them to their own epidermis.
