| A | B |
|---|
| Diploblastic | animals with only two germ tissue layers |
| Triploblastic | animals with three germ tissue layers adding the mesoderm layer in |
| Pseudocoelom | A body cavity formed by the blastocoel and not the mesoderm |
| Coelom | Fluid-filled space separating the digestive tract from the outer body wall. Formed from mesoderm tisues. |
| Protostome | Developmental mode where eight cell stage begins spirally and determinante and the the mouth develops from the blastopore |
| Deuterstome | Developmental mode where eight cell stage is radial and indeterminante and anus develops from the blastopore |
| Spiral Cleavage | Cell division planes are diagonal to the vertical axis of the embryo |
| Determinante Cleavage | Developmental fate of an embryonic cell is determined early on in the development |
| Radial Cleavage | Cell division plans are parallel of perpendicular |
| Indterminante Cleavage | Developmental fate of embryonic cells are not determined and can each become a complete embryo |
| Blastopore | Indentation that during gastrulation leads to the formation of the archenteron |
| Schizocoelous | Coelom cavity created n protostome development by split mesoderm during archenteron formation. |
| Enterocoelous | Coelom cavity formation n deuterostome development when the mesoderm buds form the archenteron wall. |
| Edicaran Fauna | First accepted animal fossils dating 575 million years old |
| Cambrian Explosion | Boom in animal diversity between 542-525 million years ago |
| Ingestion | A heterotrophic mode of nutrition in which other organisms or detritus are eaten in whole or in pieces. |
| Cleavage | The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane. Also, the succession of rapid cell divisions without growth during early embryonic development that converts a zygote into a ball of cells |
| Blastula | The hollow ball of cells marking the end stage of cleavage during early embryonic development. |
| Gastrulation | The formation of gastrula from a blastula |
| Larva | A free-living sexually immature form of some animal life cycles that may differ from the adult in morphology, nutrition, and habitat. |
| Metamorphosis | The resurgence of development in an animal larva that transforms to a sexually mature adult. |
| Bilateral Symmetry | Characterizing a body form with a central longitudinal plane that divides the body into two equal but opposite halves |
| Dorsal | Pertaining to the back (top) of a bilaterally symmetric animal |
| Ventral | Pertaining to the underside (bottom) of a bilaterally symmetric animal |
| Anterior | Referring to the head of a bilaterally symmetric animal |
| Posterior | Pertaining to the rear (tail end) of a bilaterally symmetric animal |
| Parazoa | Animals belonging to a grade of organization lacking true tissues (collections of specialized cells isolated from other tissues by membranes) ; a sponge (phylum Porifera) |
| Eumetazoa | Members of the clade Eumetazoa, animals with true tissues (all animals except sponges) |
| Radial Symmetry | Characterizing a body shaped like a pie or a barrel, with many equal parts radiating outward like the spokes of a wheel, present in cnidarians and echinoderms; also can refer to flower structure. |
| Radiata | Animals that are radially symmetric. |
| Bilateria | Animals that are bilaterally symmetric |
| Archenteron | The endoderm-lined cavity, formed during the gastrulation process, that develops into the digestive tract of an animal |
| Cephalization | An evolutionary trend toward the concentration of sensory equipment on the anterior end of the body |
| Germ Layers | Three main layers that form the various tissues and organs of an animal body |
| Ectoderm | The outermost of the three primary germ layers in animal embryos; give rise to the outer covering and, in some phyla, nervous system, inner ear, and lens of the eye |
| Endoderm | The innermost of the three primary germ layers in animal embryos; lines the archenteron and gives rise to the liver, pancreas, lungs, and the lining of the digestive tract |
| Mesoderm | The middle primary germ layer of an early embryo that develops into the notochord, the lining of the coelom, muscles, skeleton, gonads, kidneys, and most of the circulatory system. |
