Glaucus (gastropod)

Glaucus is a genus of small blue pelagic sea slugs. They are aeolid nudibranchs, ranging in size from 20 to 40 mm (0.79 to 1.57 in). They feed on colonial cnidarians such as Portuguese man o' wars, blue buttons, and purple sails. They can produce painful and potentially dangerous stings when handled, as they store the venomous nematocysts of their prey.Glaucus is the only genus in the family Glaucidae. It includes five species.

Taxonomic history

The genus Glaucus was established by monotypy in 1777 by the British naturalist Johann Reinhold Forster. He described specimens of Glaucus atlanticus recovered during the second voyage of James Cook aboard the HMS Resolution. The genus is named after the Greek sea-god Glaucus. In 1848, the German naturalist Johannes Gistel provided the substitute name Dadone for Glaucus. But it is unnecessary and is now regarded as invalid.

The family Glaucidae was established in 1827 by the British zoologist John Edward Gray to contain the genus. A second species in the family was described by the Danish malacologist Rudolph Bergh in 1860. He placed it under a new genus Glaucilla. However, the synapomorphies between Glaucus and Glaucilla have made the maintenance of both genera irrelevant. Therefore Glaucus is now regarded as the only genus within the family Glaucidae. Glaucidae is classified under the superfamily Aeolidioidea.