Cnidarians are aquatic animals with no eyes and with a body plan that exhibits radial symmetry around a single opening, or mouth. Some cnidarians permanently fix themselves by a flat base to an object, while others are bell-shaped and free-swimming. Like some cnidarians, echinoderms exhibit radial symmetry, but almost always in a five-pointed star configuration. Also, unlike cnidarians, echinoderms have a spiny outer skin.

Which pictured animal is a cnidarian?

Choice C

Explanation

The animal shown in choice (C) is the only one that exhibits radial, or circular, symmetry around a center. (The picture shows a jellyfish.)

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