Question

what is phylum Cnidaria? what are its characteristics ?​

Answer 1

Hello friend...

Cnidaria is a phylum under Kingdom Animalia containing over 11,000 species of animals found exclusively in aquatic environments: they are predominantly marine. Their distinguishing feature is cnidocytes, specialized cells that they use mainly for capturing prey.

Characteristics:- The phylum includes jellyfish, sea anemone and coral. Characterized by a digestive cavity that forms the main body, they may have been the first animal group to reach the tissue level of organization. Cnidarians are radially symmetrical, jelly-like and have a nerve net and one bodyopening.


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Answer 2

$\huge\bold{Question:}$

What is phylum Cnidaria ? Describe its characteristics ?​

$\huge\bold{Answer:}$

Cnidaria is basically a phylum which comes under the kingdom animalia.

Cnidarians are also known as coelenterates.

$\huge\bold{Characteristics\:of\:Cnidaria:}$

• These are multicellular and are diploblastic animals with tissue grade of organisation.

• A gelatinous layer mainly known as mesoglea and/or mesohyl persists between the epidermis and the gastrodermis in them.

• Their body shows radial symmetry.

• Respiratory, circulatory, and excretory organs are mainly absent.

• Their nervous system is primitive i.e., they have the network of nerve cells.

• The body shows two main forms :-

the polyps => which is diploid, cylindrical, and sedentary and is either solitary or colonial and reproduces asexually.

and the medusae => which is diploid as well and is umbrella-like and free-swimming sexual phase of the animal.

• The asexual reproduction by budding and sexual by gametes is formed by medusae.

• They are aquatic animals i.e., they live in water, mostly marine, a few such as hydra are fresh water ones.

• Some of these species likr corals or physalia live in colonies while others like hydra live solitary.

• Many of these possess a hard exoskeleton (of lime) to form corals.

Phylum Coelenterata is further divided into the following (three) classes :

$\large\bold{Class\:1.\:Hydrozoa:}$

=> Their life history basically lacks polypoid phase and has only the medusoid form.

$\bold{Examples:}$ Hydra, Obelia, Porpita, etc.

$\large\bold{Class\:2.\:Scyphozoa:}$

=> Thier life history is just the sane like hydrazoas i.e., they lack polypoid form and has only the medusoid form.

$\bold{Examples:}$ Aurelia, Rhizostoma.

$\large\bold{Class\:3.\:Anthozoa:}$

=> Thier life history is just opposite of the other two classes. t

=> Here, the medusoid form is absent whereas they only have their polypoid form.

$\bold{Examples:}$ Pennatula, Tubipora, Gorgonia, etc.