Gyrineum gyrinum (Linnaeus, 1758)
Gyrinum triton, 38mm

Gyrineum gyrinum is common to abundant on shallow lagoon reefs and pinnacles at Kwajalein Atoll, but appears to not live on the seaward reef. Curiously, despite nearly three years of exhaustive searching for nudibranchs in the typical habitats of Gyrineum at Enewetak Atoll, no living or empty shells were ever found.

The two photos below show specimens on egg masses, the upper ones deposited on a large disc of Halimeda algae and the lower on dead coral. We presume these are the eggs of Gyrineum.

This Gyrineum appears to be eating a cephalopod egg mass on an old dead fungiid coral. We have seen these shells on these kind of eggs several times. When these eggs hatch, tiny squid or octopus-like creatures come out.

An entire group of Gyrineum were found apparently feeding on an egg mass of a sea hare, Dolabella.

Created 5 August 2010
Updated 14 March 2020

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