An animal that lacks an internal body cavity (coelom)
In animals, one of the three basic types of tissue formed during gastrulation; gives rise to all other tissues
A type of metamorphosis in which the animal increases in size from one stage to the next, but does not dramatically change its body form. Also called incomplete metamorphosis.
A type of metamorphosis in which the animal completely changes its form. Also called complete metamorphosis.
A major lineage of protostomes (Liphotrochozoa) that grow by extending the size of their skeletons rather than by molting. Many phyla have a specialized feeding structure (lophophore) and/or cilitated larvae (trochophore).
A major lineage of protostomes (Ecdysozoam) that grow by shedding their external skeletons (molting) and expanding their bodies.
The free-floating stage in the life cycle of some cnidarians
The middle of the three basic cell layers in most animal embryos; gives rise to muscles, bones, blood, and some internal organs (kidney, spleen,etc.).
The outermost of the three basic cell layers in most animal embryos; gives rise to the outer covering and nervous system