Which term refers to the unique stinging intracellular structures of cnidarians?Multiple choice question.ProglottidsColloblastsSpiculesChoanocytesNematocysts

The term that refers to the unique stinging intracellular structures of cnidarians is Nematocysts.

Explanation:

Nematocysts are specialized cells found in cnidarians (such as jellyfish, corals, and sea anemones) that contain a small, coiled, harpoon-like structure. When triggered, these nematocysts can eject a barbed, stinging thread that can penetrate the skin of prey or potential threats, delivering toxins. This adaptation is crucial for their feeding and defense mechanism.

In the context of the options provided:

1. Proglottids - segments of a tapeworm, not related to cnidarians.
2. Colloblasts - cells found in ctenophores, also not related to cnidarians.
3. Spicules - structural elements found in sponges, not stinging cells.
4. Choanocytes - flagellated cells in sponges that help in feeding.

Thus, the correct answer is Nematocysts.