BIOL 111 Lecture Notes - Lecture 35: Brittle Star, Gastrulation, Blastula

• School: McGill University
• Department: Biology
• Course: BIOL 111
• Professor: Richard Roy

Document Summary

Biol 111 organismal biology: deuterostomes are divided into three groups: o echinoderms o hemichordates o chordates. Echinoderms echinoderm = spongy skin there are about 7000 known species they are strictly marine they are benthic (bottom dwellers) they have diverse modes of nutrition e. g. sea stars, sea urchins, sand dollars. Only six of about 20 groups still remain o echinoids sea urchins they have many spines for locomotion or defence they have pincers (pedicellariae) used for defence and cleaning. Have an aristotle lantern used for feeding they are herbivores sand dollars live in soft sediment and are filter feeders. Brittle stars: many arm spines filter feeders, predators, or detritivores. Much more prevalent 300-500 mya some are sessile o holothuroids sea cucumbers. Detritivores, scavengers, filter feeders they have a reduced endoskeleton they have five rows of tube feet they draws in water through the anus for respiration.