Analyzing Symmetry
Chapter 21: Sponges and Cnidarians

As animals have evolved, they have moved from having no symmetry (sponges) to radial symmetry (cnidarians), and finally to bilateral symmetry (worms, mollusks, arthropods, echinoderms, and chordates). Analyze the list of objects and decide which type of symmetry each object has. (Hint: Animals with bilateral symmetry have a definite top end and rear end, a front side and a back side, and a right side and a left side.)

Objects
door knob
fork
human
light bulb
picture of a landscape
pile of clothes
pizza pie
sunflower
tree

Analyze the Information

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1. Which objects have no symmetry?
2. Which objects have radial symmetry?
3. Which objects have bilateral symmetry?

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