BIO 2135 Study Guide - Final Guide: Planula, Triploblasty, Hydrozoa
5 Apr 2014
School
Department
Course
Professor
Document Summary
Chitinous pen inside mantle is all that remains of shell, aids in protecting internal organs when mantle contracts. Role for edge of mantle is to lock/seal out water at collar, cavity aids in jet propulsion. 3 hearts (2 brachial -> body to ctenidia. 1 systematic -> gills to rest of body. Each brachial heart connected to pericardial gland) Ctenidia: respiratory organ, no cilia (muscle contractions move water over surface) has concurrent blood flow, less efficient than countercurrent flow. Ganglia of tetraneural system have been consolidated in brain not elsewhere: reason for giant axons, which connect brain to rest of body large nerve cord, olfactory system. Dorso-ventrally elongated - but distance between head and foot is shorter. Jet propulsion by pumping water thru funnel (modification of foot), closing collar to water. Cilia also found in metanephridium ( the tubules carrying excretory waste from coelom) 1 heart in ancestral pericardial cavity, open circulatory system.
