Favorinus japonicus Baba, 1949
These well-camouflaged eolids prey exclusively on the
eggs of other sea slugs. In Hawai`i they are most easily observed on the
large red or pink coiled ribbons of the Spanish Dancer, Hexabranchus
sanguineus. Gently spread the rosette of eggs to find them. Like worms
in the heart of a rose, they devour the flower from the inside. Often
their white egg coils can be seen as well——eggs on eggs. The animals
are pink, whitish or greenish, depending on the color of the eggs
they consume. Nudibranch eggs are often poisonous and these predators
probably incorporate the toxins for their own defense. Unlike some
other eolid nudibranchs, they have no sting. They attain about 1/2
in. (1.25 cm) and are known from Japan, Guam and Hawai'i. Thanks to
Linda Bail of Bubbles Below Scuba Charters
for showing me how to find these wonderful slugs and to Dan Dickey my
summer dive buddy for spotting this one off Oahu's north shore and holding down the egg
coil for the photo.
We have also seen Favorinus japonicus in the Philippines, in addition to Favorinus tsuruganus.
Hawaii's Fishes, a Guide for Snorkelers, Divers and Aquarists Mutual Publishing, 1993
Hawaii's Underwater Paradise, Mutual Publishing, 1997
Hawaii's Sea Creatures, a guide to Hawaii's Marine Invertebrates. Mutual Publishing, 1999.
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