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hydroid
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Hydra
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Hydra
Hydra A new hydra (Hydra) can be seen budding from an existing one. The new hydra is a smaller and paler version of the first one.

hydroid

cnidarian class
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Also known as: Hydrozoa
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hydroid, any member of the invertebrate class Hydrozoa (phylum Cnidaria). Most hydroids inhabit marine environments, but some have invaded freshwater habitats. Hydroids may be either solitary or colonial, and there are about 3,700 known species. Hydroids have three basic life-cycle stages: (1) a tiny free-swimming ciliated planula larva about 1 mm (0.04 inch) long, which settles and metamorphoses into (2) a sessile (attached), usually colonial polyp stage, which in turn liberates (3) a gamete-producing male or female medusa (“jellyfish”). This cycle is exemplified by the genus Obelia, whose members are widely distributed throughout the world. Many hydroids have, through evolution, ...(100 of 304 words)

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