Multiple choice

Which of the following is not an echinoderm?

  1. Star fish

  2. Sea urchin

  3. Hydra

  4. Antedon
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Star fish, Sea urchin, and Antedon (feather star) are all echinoderms characterized by radial symmetry, water vascular system, and spiny skin. Hydra is a cnidarian (related to jellyfish and corals) with tentacles and stinging cells (nematocysts), not an echinoderm.

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