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characteristics of an animal

-sexual reproduction
-motility (moves)
-no cell wall

two major divisions

-invertebrates (no back bone)
-vertebrates (back bone)


a group of cells that have the same function


layers of cells that give rise to organs

three derms



nervous system, sense, skin


skeletal system, muscle system, circulatory system

symmetry (three types)

-radial symmetry
-bilateral symmetry


fluid filled cavity laying within cells produced by mesoderm


animal with no coelom


coelon that is within cells produced from mesoderm and endoderm


has coelom


an embryonic stage that marks the end of cleavage during animal development; a hollow ball of cells in many species.


the embryonic stage resulting from gastrulation in animal development. most animals have a gastrula made up of three layers of cells: endoderm, ectoderm, and mesoderm

body cavity

a fluid containing space between the digestive tract and the body wall.

hydrostatic skeleton

a skeletal system composed of fluid held under pressure in a closed body compartment; the main skeleton of most cnidarians, flatworms, nematodes, and annelids.


the animals with "true tissues" (all animals except sponges)


animals that exhibit bilateral symmetry

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