Trachomedusae

Trachomedusae

 

(also Trachymedusae), an order of marine coelenterates of the class Hydrozoa. The Trachomedusae have eight sex glands arranged along radial canals, and numerous delicate tentacles on the margin of the umbrella. The life cycle lacks a polypoid generation. A planula develops from the egg and is transformed into an actinula-like larva, which metamorphoses into a young medusa. There are approximately 50 species, ten of which are found in the USSR. Aglanta digitale, the commonest species of its genus, is found in almost all oceans. Deep-sea species are reddish or brownish in color and are capable of luminescence.

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