It looks like one of the creatures from Guilhermo del Toro's movies, but is real. And cute!
But, despite of its looks, this tiny animal who spends its life floating upside-down wherever the currents and wind take it, on the surface of the Pacific, Atlantic or Indian Oceans - thanks to an air bubble inside its belly -, the blue sea slug is not that innocent.
In fact, it stores the swallowed poison of highly poisonous hydrozoans ir feeds upon (such as the Portuguese Man-O’-War) inside the up to 84 finger-like structures or cerata sticking out of its body, and then uses this poison to defend itself against other predators! Like some other sea slugs, it can swallow the prey’s stinging cells (the nematocysts) without hurting itself by releasing protective mucus and by hard barrier-like discs inside its skin. The ocean slug also has a form of camouflage called countershading that protects it from both flying and swimming predators while it floats: the underside of the blue glaucus (which faces upward) is blue, helping it blend into the water’s surface when seen from above, while its back (which faces downward) is a more grayish color, helping it blend into the ocean when seen from below.
But, despite of its looks, this tiny animal who spends its life floating upside-down wherever the currents and wind take it, on the surface of the Pacific, Atlantic or Indian Oceans - thanks to an air bubble inside its belly -, the blue sea slug is not that innocent.
In fact, it stores the swallowed poison of highly poisonous hydrozoans ir feeds upon (such as the Portuguese Man-O’-War) inside the up to 84 finger-like structures or cerata sticking out of its body, and then uses this poison to defend itself against other predators! Like some other sea slugs, it can swallow the prey’s stinging cells (the nematocysts) without hurting itself by releasing protective mucus and by hard barrier-like discs inside its skin. The ocean slug also has a form of camouflage called countershading that protects it from both flying and swimming predators while it floats: the underside of the blue glaucus (which faces upward) is blue, helping it blend into the water’s surface when seen from above, while its back (which faces downward) is a more grayish color, helping it blend into the ocean when seen from below.
~Ally