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animals with no backbone


animals with a backbone

feedback inhibition

a mechanism of homeostasis where the body reacts to something in the external world (ex: getting hot and sweating)


hollow ball of cells


an animal whose mouth is formed from the blastopore


animal whose anus is formed from the blastospore


opening through which waste leaves the digestive tract


inermost germ layer


middle germ layer


outermost germ layer

radial symmetry

symmetry going around in a circle across the body

bilateral symmetry

symmetry that can split into two identical parts


concentration of sense organs and nerve organs at the front end of the body


specilized cells that use flagella to move a steady current of water through the sponge


spike-like structure made of chalklike calcium carbonate or glasslike silica


specialized cells that move around within the walls of the spong

internal fertilization

fertilization in the inside of the body


immature stage of an organism


groups of archaeocytes surrounded by a tough layer of spicules


poison-filled sting structure that contains a tightly coiled dart


stinging cells located along tentacles in which cnidarians get their name


a cylindrical body with armlike tentacles; mouth points upwards, routed to ground


motile, bell-shaped body with a mouth on the bottom

gastrovascular cavity

digestive chamber with one opeing

nerve net

a loosely organized network of nerve cells that together allow cnidarians to detect stimuli

hydrostatic skeleton

consists of a layer of circular muscles and a layer of longitudinal muscles that (along with the nerve net) enable the body to move

external fertilization

fertilization on the outside of ones body

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