Elysia pusilla

Kingdom: Animalia
Phylum: Mollusca
Class: Gastropoda
Order: Sacoglossa
Family: Plakobranchidae
Genus: Elysia
Species: Elysia pusilla

Elysia pusilla is a small sacoglossan, or sap-sucking sea slug, from the family Plakobranchidae. Like other sacoglossans it is not a true nudibranch.

It is green and flattened, with a shape and texture that blend in almost perfectly with the algae it lives on. Spotting one usually means looking for something that does not quite match the plant.

It feeds on Halimeda, the green alga made of small coin-shaped segments. Like other Elysia it keeps chloroplasts from its food and can use them to make energy from sunlight.

Check Halimeda patches on shallow sand and rubble slowly, segment by segment. A macro lens and side lighting help separate the slug from its background.

It appears on page 360 of Nudibranchs of the Philippines.

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