Animal Characteristics and Development

Flashcards covering animal characteristics, body plans, germ layers, coeloms, and embryo development.

What are the characteristics shared by most animals?

Eukaryotic, multicellular, heterotrophic, aerobic, develop from an embryo, reproduce (mostly) sexually, motile at some stage, possess nervous and muscle tissue (mostly).

What is a zygote?

A fertilized egg.

What is a blastula?

A ball of cells formed from a zygote undergoing mitosis.

What is gastrulation?

The process where the blastula folds inward, forming three tissue layers.

What are the three germ layers formed during gastrulation?

Endoderm, mesoderm, and ectoderm.

What characteristics do animals with radial symmetry have?

Round shape, difficult to distinguish left from right (mirror image if cut in half).

What characteristics do animals with bilateral symmetry have?

Elongated shape, distinct left and right sides, top and bottom sides.

What characteristics do animals with asymmetrical symmetry have?

Uneven shape that doesn't fit into radial or bilateral categories.

What is the anterior region?

Head or front region.

What is the posterior region?

Region away from the head (back or tail region).

What are animals with three germ layers described as?

Triploblastic (endoderm, mesoderm, ectoderm).

What are animals with two germ layers described as?

Diploblastic (endoderm and ectoderm).

What is a coelom?

A true body cavity lined with mesoderm tissue.

What is a pseudo coelom?

A false body cavity not completely lined with mesoderm tissue; originates from the blastocoel.

What is an acoelomate?

An animal with no body cavity (body is completely solid).

What is protostome development?

Embryonic development characterized by spiral cleavage and determinate cells.

What is deuterostome development?

Embryonic development characterized by radial cleavage and indeterminate cells.

In protostome development, what does the first pore to form become?

The mouth.

In deuterostome development, what does the first pore to form become?

The anus.

What is schizocoelous?

The way the body cavity is formed in protostome development where mesoderm tissue develops into the coelom.

What is enterocoelous?

The way the body cavity is formed in deuterostome development where mesoderm splits off from the archenteron to form the coelom.

What algae are believed to be the common ancestor of all animals?

Choanoflagellates.