It’s light blue, and it looks like a lizard, the dark-blue coloration on its back outlining its body. The marine animal’s feet are quite different from those of a reptile, though, seeming to explode in bizarre starbursts, the spiky rays of which differ in length from one another. Although it’s usually called a blue dragon, scientists know it as Glaucus atlanticus, a type of nudibranch, a gastropod without a shell or true gills. Normally, the blue dragon floats in the ocean, but the wind sometimes blows a whole “fleet” of them onto Australian beaches. Besides the 3-centimeter-long Glaucus atlanticus, the 13-centimeter-long Glaucilla marginate, also a nudibranch that closely resembles its smaller cousin and is likewise called a blue dragon, occasionally blows ashore.
Both the smaller and the larger blue dragons belong to “the pleuston, which lives partly in the water and partly in the air and relies on the winds to carry them places.” Although blue dragons can’t swim against ocean currents, the tiny animals are able to spin themselves around and to perform “somersaults” by sucking air into themselves. The air forms a bubble inside them, helping them “stay afloat and [to remain] upside down.”
Despite their restricted mobility, blue dragons are predators “in their own small world,” feeding on blue buttons (colonies of hydroids) and bluebottles (colonies of polyps), while relying on their coloration to “blend in” with the ocean’s surface and avoid attacks by other predators.