Marionia arborescens

Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Order: Nudibranchia
Family: Tritoniidae
Genus: Marionia
Species: Marionia arborescens

Marionia arborescens is a tritoniid nudibranch. Its name means tree-like, after the branching gills that run along the edges of its back.

This one is white to pale green with frilly gills, and it was photographed on an orange sponge. The front of the head carries a veil with small finger-like processes, typical of tritoniids.

Tritoniids generally feed on soft corals and sea fans, and many blend in well with their hosts, so they are easy to swim past.

Take your time on soft corals and look for the frilly outline of the gills. A side view at the slug's level shows off the branching shape best.

It appears on page 205 of Nudibranchs of the Philippines.

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