BIOL 111 Lecture 18: Echinoderms and Chordates

• School: McGill University
• Department: Biology
• Course: BIOL 111
• Professor: Andrew Hendry , Elena Melania Cristescu , Anna Lesley Hargreaves

Document Summary

Protostomes= blastopore develops into a mouth & mesoderm splits to form the coelom. Priapulid worm (is a protostome but has its blastopore developed into an anus) Deuterostomes== blastopore develops into an anus & archenteron out pockets to form coelom: echinoderms, chordates. Echinoderms like sea urchins have pentaradial symmetry as adults but bilateral symmetry as larvae. They lost their bilateral symmetry during the metamorphosis of the larva and developed a radial symmetry. Aboral surface (opposite to the mouth): madreporite, anus. It involves the entrance of water from the outside through the madreporite (have a sieve that can stop non-water particles from coming in) to their circulatory system. Water vascular system: (closed system: used for locomotion, feeding, gas exchange & excretion, closed system , have sensory structure (chemical & tactile, locomotion: It circulates through the ring canal and then in each arm. The ampulla is then squeeze by the muscles around.