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Blue Dragon | Daily Animal Facts

Animal profile

Blue Dragon

Glaucus atlanticus

GastropodaOpen-ocean surface waters, floating upside down at the air-water interface

Field profile

The blue dragon is a small pelagic sea slug, typically under four centimetres long, that floats belly-up at the ocean surface using a gas bubble held in its stomach. It preys on siphonophores including the Portuguese man o' war. Its blue-and-silver colouring is countershading for a life spent at the surface.

Scope note

This is an editorial profile, not a diagnostic field-identification guide or a substitute for current conservation assessments. Follow the cited sources on each fact for the evidence trail.

Published field notes

2024-04-07

Blue Dragon

The blue dragon floats belly-up and swims inverted

Glaucus atlanticus swallows air into a stomach sac to stay buoyant, drifting with its foot uppermost. Because it is upside down, its camouflage is reversed: the blue side faces the sky and the silver side faces down.

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