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Unformatted text preview: animals (such as humans, Figure 3) have only a single plane of symmetry that produces mirror halves. Bilaterally symmetrical animals tend to be active and to move forward at an anterior end, which eventually led to concentration of sensory organs in the anterior end, or head (a trend known as cephalization). Body Cavity and Development Acoelomate animals (like flatworms and flukes, shown in Figure 4) do not have a coelom (or body cavity) produced during preadult development. Pseudocoelomate animals (such as roundworms) have a body cavity but it does not develop from splitting of the mesoderm embryonic tissue layer. Coelomate animals (humans, fish, shrimp, such as shown in Figure 4) have a body cavity lined with mesoderm cells....
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- Fall '10