It sounds like a fantasy character, but Glaucus atlanticus, commonly called the blue dragon, is a real sea slug.
Its appearance is remarkable. Its lifestyle is even more surprising.
It floats upside down at the ocean’s surface. A gas-filled sac helps keep it afloat as it drifts and encounters its prey. Source: Australian Museum
And that prey includes bluebottles—the stinging marine animals many beachgoers know to avoid.
The blue dragon can retain stinging cells from its prey and use them for its own defense. Its delicate appearance is therefore a poor reason to pick it up. Observe it without handling it. Source: Australian Museum’s Sea Slug Forum
Those elaborate branches make it look like something invented for a film. Yet the most extraordinary detail is hidden from view: this small animal turns its prey’s defenses into its own.
The accompanying image is an AI-generated illustration, not a wildlife photograph or an identification guide.
