| A | B |
|---|
| An animal with a mouth that develops from the opening in the gastrula | protostome |
| Opening in an echinoderm for water to enter and exit | madreporite |
| Describes organisms that do not move from place to place | sessile |
| Body cavity partly lined with mesoderm, such as found in roundworms | pseudocoelom |
| Layer of cells lining the inner surface of the gastrula | endoderm |
| A fluid-filled body cavity completely surrouded by mesoderm | coelom |
| Body plan of an organism that can be divided down its length into right and left halves that form mirror images | bilateral symmetry |
| Layer of cells on the outer surface of the gastrula | ectoderm |
| Animal in which the anus develops from the gastrula's opening | deuterostome |
| Mammal that reproduces by laying eggs | monotreme |
| Animal that has three cell layers, with a digestive tract but no body cavity | acoelomate |
| Body plan that can be divided along any plane, through a central axis, into roughly equal halves | radial symmetry |
| Middle cell layer formed in the developing embryo | mesoderm |
