Biology / Unit 12 Bio 2721 short lesson, about 20 seconds
Body Plans and the Symmetry Constraint
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The idea
An animal's symmetry plan, per Bio 2219, constrains how its body can be organized: bilateral symmetry permits a head end, and with it centralized sensing and directional movement.
In practice
A sponge is asymmetrical, a sea anemone is radial, and a goat is bilateral.
Where people slip
Radial animals are not "simpler bilateral animals" — the two plans suit different feeding strategies instead.
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