Which of the following structures is NOT found in sponges?

Sponges, belonging to the phylum Porifera, have a distinctive set of structures that enable their simple yet effective way of life. They do not possess cnidocytes, which are specialized cells found in cnidarians (such as jellyfish, corals, and sea anemones) that are used for capturing prey and defense. Instead, sponges have other important structures.

Spicules are microscopic skeletal elements made of calcium carbonate or silica, providing structural support. Amoebocytes are versatile cells within sponges that perform various functions, including nutrient transport, waste removal, and reproduction. Choanocytes, or collar cells, line the inner chambers of sponges and are crucial for filter feeding, as they create water currents and trap food particles.

In summary, the absence of cnidocytes is a defining characteristic of sponges, highlighting their unique biological structure and function compared to other animal groups.