Depends On How You Cut It
Chapter 24: Echinoderms and Invertebrate Chordates

The natural world provides many examples of both bilateral symmetry and radial symmetry. Organisms that have radial symmetry have body parts that radiate from a central point. Organisms that have bilateral symmetry have body parts that are arranged around a midline. You can see examples of both bilateral symmetry and radial symmetry if you…

Try This

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1. Cut an apple in half from top to bottom. (Be careful when using a knife.) Look at the cut surface and note the type of symmetry represented.
2. Cut another apple across the middle (cross-section). Look at the cut surface and note the type of symmetry represented.

Analyze Your Results

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1. What type of symmetry did you obtain from a longitudinal section?
2. What type of symmetry did you obtain from a cross-section?
3. Which part of the apple—the longitudinal cut or the cross-section cut—most resembles the symmetry found in echinoderms?

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