Blastula
early animal embryo consisting of a hollow ball of cells
Gastrula
advanced animal embryo consisting of two or more tissue layers
Invertebrate
animal with no backbone
Vertebrate
animal with a backbone
Eumetazoa
animals with tissues
Parazoa
animals with no tissues
Bilateral symmetry
body symmetry where the body can be divided into two identical halves
Radial symmetry
body symmetry where the body can be divided into multiple similar parts
Cephalization
concentration of sensory organs and brain at the head
Ectoderm
outer tissue layer, becomes skin and nervous system
Endoderm
inner tissue layer, becomes digestive system
Mesoderm
middle tissue layer, becomes muscles and circulatory system
Deuterostome
organisms that develop “anus first”
Protostome
organisms that develop “mouth first”
Coelom
body cavity