What is a cnidarians?

Answer 1

Cnidarians are actually carnivorous fauna. Cnidarians are either polyps, such as sea anemones or coral, or free-floating medusae, such as jellyfish.
Polyps have a tube-like body with an opening on top that is surrounded by outward- and upward-facing tentacles.
Medusae are usually bell-shaped animals with a concave oral surface, or mouth, and tentacles that dangle downward from the rim of an umbrella-like body.

Four classes make up the phylum Cnidaria:
Anthozoa, which includes sea anemones and coral
Cubozoa, which includes Portuguese man-of-war
Hydrozoa, which includes jellyfish
Scyphozoa, which includes box jellies

Cnidarians live in aquatic environments and inhabit all depths, from the sandy substrate up to the surface. Some are even found in freshwater.
Cnidarian bodies have only one opening that serves as both mouth and anus. Food enters through the mouth and excess food and waste leave through the mouth as well.
Cnidarians have no need for a brain or a heart; instead, these animals have specialized tissues to coordinate basic bodily functions. A decentralized net of nerves and receptors allows the animals to negotiate their environment, whether they are moving about, detecting danger, or making a meal of any prey that swims by.

Answer 2

the phylum cnidaria consists of about 10,000 species which are mostly marine. the jellyfish and sea anemone belong to this phylum. there bodies are radially symectrical. they capture there prey by stining them with tentacles, there tentacles have special cells that contains a toxin. the only have one body opening to food and wate exit and enter through the same opening. the are both aquatic floating and sessile (meaning they don't move). they have a simple nervous system. they have s bodt forms polyp or medusa.

Answer 3

A jelly fish. Cnidarian's have a sting cell called a cnidnocyte which is the defining feature.