Table of Contents
Cnidaria
Cnidaria is a large phylum under the Animal kingdom that houses about 11,000 species. They are aquatic animals that are found in both fresh and marine water. The characteristic feature of the phylum is the presence of cnidocytes. They are specialised cells that help in capturing prey by stinging.
They exist in two body forms: a swimming medusae and a sessile polyp. Both the body forms are radially symmetrical and bear tentacles that consist of cnidocytes. They have one orifice and a body cavity that is used for respiration and digestion.
Ecologically, they are predators that prey on planktons and other marine animals bigger in size than their own. They mainly obtain their nutrition from dinoflagellates. A few of them are parasitic in nature as well. Examples of the phylum include: jellyfish, sea anemone, corals and Hydra.
Ctenophora
Ctenophora is a phylum under the Animal kingdom that is mainly composed of marine invertebrates that are found in sea waters globally. The characteristic feature of this phylum is the presence of groups of cilia (referred to as combs) that help them in swimming.
Around 150 species of the phylum are known. Their size ranges from a few millimetres to about 1.5 metres. The body of a ctenophora is composed of a mass of jelly, with a two-cell-thick layer on the outside and another on the inside. They have various body forms such as retractable tentacles that help to capture prey (cydippida); flat, dorsiventral combless body (platyctenida); and large mouthed organisms (beroida).
Ecologically, all ctenophores act as predators. They prey on microscopic larvae to small crustaceans. Examples of the phylum include: Pleurobrachia, Euplokamis and Bathocyroe.
Refer: Ctenophora – NEET Biology Notes
Cnidaria vs Ctenophora
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Cnidaria is a diverse phylum that is composed of aquatic animals. |
Ctenophora is a small phylum that is composed of marine invertebrates. |
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The presence of cnidocytes is the characteristic feature of the phylum. |
The presence of groups of cilia is the characteristic feature of the phylum. |
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They are found in both marine and freshwater habitats. |
They are found exclusively in marine environments. |
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They are highly diversified. |
They are less diversified. |
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Majority of the cnidarians are predators but some are parasitic as well. |
All the ctenophores are predators. |
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They prey upon planktons and dinoflagellates. |
They prey on microscopic larvae and small crustaceans. |
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They can either be sessile or free swimming. |
They swim with the help of comb plates. |
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Sea anemone, jellyfish and Hydra. |
Pleurobrachia, Euplokamis and Bathocyroe. |
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