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One of the special characters of Coelenterata is the occurrence of
A. Hermaphroditism.
B. Flame cells
C. Polymorphism
D. Nematocysts.

Last updated date: 13th Jun 2024
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Hint:All coelenterates are aquatic, mostly marine. The body form is radially symmetrical, diploblastic and does not have a coelom. The body has a one hole, the hypostome, surrounded by sensory tentacles equipped with a barbed or venomous coiled thread to capture mostly planktonic prey.

Complete Answer:
To answer this question, first, we need to know about Coelenterata. Phylum Coelenterata is a group of aquatic or marine organisms and a member of the Animal kingdom. They are usually found attached to the rocks at the beneath of the sea. These are the multicellular and simplest group of invertebrate animals, found in colonies or solitarily.

Now, let us find the solution from the option.
Hermaphroditism is the condition of having both male and female reproductive organs. Hermaphroditic animals are mostly invertebrates such as worms, bryozoans (moss animals), trematodes (flukes), snails and slugs etc.
A flame cell is a specific excretory cell present in the simplified pure water invertebrates consisting of flatworms, rotifers and nemerteans.
Polymorphism is the occurrence of two or more clearly different morphs or forms, also referred to as alternative phenotypes, in the population of a species.
Coelenterates are acoelomate. They have a one hole that functions as the mouth and anus. The hole is enclosed by tentacles. The tentacles consist of specific types of cells known as nematocysts are located in Coelenterata only. These cells are used for food catching, defensive and offensive purposes. And also nematocysts cells serve to immobilize prey with toxins contained within the cells. Nematocysts contain coiled threads that may bear barbs.

Thus, the correct option is D. i.e. Nematocysts.

Note:Coelenterata have very simple tissue organization, with only two layers of cells (external and internal), and radial symmetry. Some examples are corals, which are typically colonial, and hydra, jellyfish and sea anemones which are solitary. Coelenterata lack a specialized circulatory system relying instead on diffusion across the tissue layers.