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27 terms

Chapter 26 Sponges and Cnidarians

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invertebrate
animals with no backbone
vertebrate
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)
blastula
hollow ball of cells
protostome
an animal whose mouth is formed from the blastopore
deuterostome
animal whose anus is formed from the blastospore
anus
opening through which waste leaves the digestive tract
endoderm
inermost germ layer
mesoderm
middle germ layer
ectoderm
outermost germ layer
radial symmetry
symmetry going around in a circle across the body
bilateral symmetry
symmetry that can split into two identical parts
caphalization
concentration of sense organs and nerve organs at the front end of the body
choanocytes
specilized cells that use flagella to move a steady current of water through the sponge
spicule
spike-like structure made of chalklike calcium carbonate or glasslike silica
archaeocytes
specialized cells that move around within the walls of the spong
internal fertilization
fertilization in the inside of the body
larva
immature stage of an organism
gemmules
groups of archaeocytes surrounded by a tough layer of spicules
nematocyst
poison-filled sting structure that contains a tightly coiled dart
cnidocytes
stinging cells located along tentacles in which cnidarians get their name
polyp
a cylindrical body with armlike tentacles; mouth points upwards, routed to ground
medusa
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