Glaucus atlanticus (common names include the blue glaucusdragon slug) is a species of small, blue (open-ocean) aeolid nudibranch, a shell-less Glaucidae These sea slugs are ; they float upside down by using the of the water to stay up, where they are carried along by the winds and ocean currents.

The mythical Blue Glaucus, or Glaucus atlanticus as known by its scientific name, is a small-sized blue sea slug species. It has distinctive dazzling blue hues that have garnered it plenty of attention in recent years. These colors have also inspired a series of nicknames, such as blue dragon, sea swallow, and blue angel.

The blue dragon (Glaucus atlanticus) is a type of mollusk known as a nudibranch. Despite its impressive appearance, it rarely grows larger than three centimeters long. It can be found drifting on the surface of the Atlantic, Pacific and Indian oceans in temperate and tropical waters.

Scientifically known as Glaucus atlanticus, blue dragons are a pelagic nudibranch that sails on the surface of the ocean, the institute explained. The creatures typically measure an inch long and feed on the toxins of larger species like the Portuguese man o' wars, which have tentacles measuring around 30 feet.