BIO 2135 Study Guide - Midterm Guide: Gastrovascular Cavity, Siphonoglyph, Planula
23 May 2016
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Innovation-gap junctions, true tissues including basement membrane digestive epithelium, oral aboral symmetry. Cnidaria-cnidocytes, polyp body, epitheliomusculature (myoneme fibres), planula larva. Cnidocyte-stinging cell, nematocyst-organelle in cnidocyte, grows under pressure. Polyp-cup shaped, epidermis, mesoglea, gastrodermis, gastrovascular cavity, digested food absorbed by phagocytosis. Hydrostatic skeleton-epitheliomuscular cells (long) nutritive muscular cell (circular) Anthozoan-biradial, siphonoglyphs pump water, muscular septa to contract, gonads in gastroderm. Eg anemone-pharynx leads to cavity, after contracting septa, pumps water with siphonoglyph into cavity, retractor muscles not mesoderm. Cnidarian innovations-dimorphic life cycle, medusa with more mesoglea to open dome, strobilazation- layers of discs, develop tentacles. Canal system-food circulates and digests, comes back to be expelled. Gonads beside digestive system, use nutrients to make gametes. Edge of medusa-statocysts detect gravity, rhopalia detect light, partly covered by hood to tell direction. Pedalia swings in to move food into mouth. Rhopalium-statocyts with statolith, lens eye, sees image not light. Hydrozoan-obelia-colonial-gastrozooid to feed, gonozooid for gonads, back to dimorphic.
