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Gonionemus is a type of hydrozoan that uses adhesive discs near the middle of each tentacle (visible as light spots on the tentacles in the photo) to attach to eelgrass, sea lettuce or various types of algae instead of swimming. They are small (bell diameter to 25 mm) and hard to see when hanging on to swaying seaweed. Nevertheless they are capable of swimming when necessary. The bell is transparent, revealing the four orange to yellowish-tan gonads that lie along most of the length of the four radial canals. The pale yellow manubrium has four short frilly lips. Up to eighty tentacles line the bell margin, with about an equal number of statocysts. Copepods are a favored prey. Whereas Pacific Northwest Gonionemus vertens lacks a sting that is felt by people, the same species in the Russian Far-East is known to be venomous. This nearshore limnomedusa inhabits quiet waters of northern Japan and Kamchatka (Russia), and the area from Alaska's Aleutian Islands to northern California.
