Animal Origins and Evolution of Body Plans By

Animal Origins and Evolution of Body Plans By: Sara Maxon Andrew Hollenbeck

What Characteristics distinguish the Animals? Animals share a set of derived traits including similarities in their sequences of many of their genes, structure of their cell junction and components of their extracellular matrix.

Embryotic Development Diploblastic- Animals with 2 embryotic layers Triploblastic- Animals with 3 embryotic layers Protostomes- mouth arises first and anus forms later Dueterostomes- anus forms first an mouth forms later

What are features of animal body plans? Animal body plans can be described in terms of symmetry, body cavity structure, segmentation, and types of appendages

Most animals have… Radial Symmetry- When one half of the body is mirror to the other. Usually move slowly or not at all. Bilateral Symmetry- When only the right of left half are mirror to the other. Usually moves rapidly. Cephalization (Sensory and nervous tissues in an anterior head)

Animals can be described as… Acoelomates- lacks enclosed fluid filled body Pseudocoelomates- animals have a fluid filled space where internal organs are suspended Coelomates- animals have a body cavity that develops within the mesoderm

How do animals get their food? Motile animals move to find food. While sessile animals stay in place and get food by filter feeding. (strains small organisms and organic molecules from their environment)

Life cycles among animals? Dispersal stage- when animals move so they don’t die where they were born.

Major groups of animals? Sponges- no true cell layer or organs Placozans- have few cell types and actual organs Ctenophores- have 2 cell layers and are separated by a inert extracellular matrix called mesoglea

The life cycle of most cnidarians has two distinct stages; a sessile polyp stage and a motile medusa stage. A fertilized egg develops into a free swimming larval planula, which settles to the bottom and develops into a polyp.

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