Nematocysts are specialized stinging cells that are formed and used only by Cnidaria. While some other organisms such as flatworms and some fish may "steal" nematocysts, they are not originally developed by them. Nematocysts are not found in sponges or as free-living symbionts, and while remnants of nematocysts may be found in some higher groups, they are not highly developed or actively used.

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Nematocysts Are

Question 6

Multiple Choice

Nematocysts are

A) widespread among the animal kingdom but first developed by Cnidaria.
B) formed and used only by Cnidaria although a few other organisms may "steal" them.
C) first found in sponges, most highly developed in cnidarians, but still found as remnants in some higher groups.
D) actually free-living symbionts that are most usually taken up by cnidarians, as are many green algae.
E) None of the choices are correct

Correct Answer: