June 25, 2017


One common type of Cnidaria is the Jellyfish

One common type of Cnidaria is the Jellyfish

Cnidaria are a class of invertebrates found in aquatic or marine environments. The name Cnidaria comes from the Greek word “cnidos,” meaning stinging nettle. There are about 9,000 species of cnidaria, the most common being the jellyfish, sea anemone, and coral. Cnidaria come in two different body forms: free-floating or free-swimming form such as the jellyfish, and the stationary form such as the sea anemone. Both forms consist of a body surrounded by  tentacles with stinging cells called cnidocytes. The body has a single opening or mouth, for taking in food and expelling waste.

Cnidaria have no organs, just a stomach cavity for digesting food. Cnidarians are carnivorous. They prey on organisms ranging in size from small plankton to larger animals such as starfish, sea slugs, fish and turtles. They capture prey using their tentacles. When prey comes in contact with the tentacles, harpoon-like stingers inject a toxin into the prey paralyzing or killing it. The cnidaria then uses its tentacles to push the prey into its mouth.

Humans frequently come in contact with cnidaria, particularly jellyfish. Most toxin from cnidaria tentacles do little more than irritate human skin. However, with some forms of cnidaria such as the sea wasp a sting can be deadly.

For more information on the Cnidaria see the Kidport cnidaria videos.


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  2. Meggie Rollins says:

    Wow! This is interesting!

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