The blue sea dragon, commonly known as the blue glaucus, is a little blue sea slug found in open water.
It is usually observed floating on the surface with its blue side facing up, blending in with the blue of the water.
Venomous species, such as the Portuguese man o' war, are part of the blue sea dragon's diet.
They store the poison from their prey in their cerata, making them much more dangerous.
It is also used to defend itself from predators.
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