While taking a swim in the tropical or intemperate waters of the World Ocean be cautious if meeting a tiny blue or blue-white sea creature, resembling a tiny fairytale dragon. It is a blue sea slug, also called a blue dragon belonging to the Glaucidae family of gastropod mollusks. Glaucus atlanticus, which is a scientific name for a blue sea slug, is a tiny, only about 1.2 inches in length, but a highly venomous creature.
It is commonly swimming up side down in the deep waters around Australia,Africa, or Europe using a protective technique called countershading when it`s top silvery grey part is actually faces the depth, protecting it from underwater predators, while it`s pale “belly” faces up doing the same against predators in the air. This trick is achieved when a sea slug swallows an air bubble and keeps it in a stomach.
So, while swimming it may meet a Portuguese Man o`War, a much larger creature with tentacles of about 30 feet long, bond itself to this large mollusk and start consuming it completely using his radula, which is sometimes compared to a chitinous tongue. The small blue dragon does not only feeds on this creature, but also saves it`s venom located in the special cells-nematocysts for a future use in its long, finger-like projections, called cerata. This tiny predator has an immunity to his large victim`s venom and accumulating it is able to produce a very painful sting if touched. It can also feed on other sea species, such as a violet snail or a blue button, but occasionally can become cannibalistic.
During a mating period, this hermaphrodite sea slug, having both male and female reproductive organs mates with a partner while his “belly” faces up and later both sea slugs produce strings of eggs.