Question

Nematocysts are found in animals belonging to the phylum

Answer 1

A nematocyst or a cnidocyte is a type of an explosive cell which contains an enormous organelle known as a cnidocyst. The cnidocyst is secretory in nature and delivers a sting to other organisms in defence. The function of cnidae is to capture the prey and to defend against the predators.

Complete answer: Nematocysts or cnidocytes are a type of cells found in animals belonging to the phylum Coelenterata. The presence of cnidae cells separates jellyfish and other coelenterates from other animals and groups. The presence of these cells defines the whole phylum Cnidaria or Coelenterata. A cnidocyte delivers or fires a sting that has a toxin inside the cnidocyst. This toxin is responsible for the stings fired by a coelenterate or a cnidarian. The nematocyst is a minute, elongated, and spherical capsule which is present exclusively in the members of the phylum Coelenterata which contains jellyfish, corals, and sea anemones. A number of capsules are present on the body surface of these animals. Each capsule is produced by a distinct cell known as the cnidoblast.
So, the correct answer is option A.
Additional Information:
There are more than 30 types of cnidae cells present in various cnidarians. These cells are broadly classified into three groups, namely, penetrant cells, glutinant cells, and volvent cells.

Note: A cnidocyte has an organelle known as a cnida. It is also denoted by various names such as cnidocyst, nematocyst, ptychocyst, or spirocyst. This organelle has a bulb-shaped capsule in which a coiled hollow tubule structure is attached. A cnidoblast or nematoblast is the term used to denote an immature cnidocyte.