Weird creature of the month – June

Sea Angel diving krabi ao nang thailandSea Angel (gymnosomata)

Light reflects through tiny creatures fluttering their translucent wings. They seem to be flying, even thou they are in the blues of our seas. These beautiful organisms are the proof of the existence of angels, angels with horns. The angel-like appearance resembles that of their huge importance in ecosystem. They are a parts of the food chain serving as the food to fishes as well as whales. Their horns may symbolically remind of the “devilish” side of these angels as predators.

Sea angels are very small swimming sea slugs found around the world in arctic and tropic seas usually in the upper 0-20m of water. They belong to marine mollusks and are divided into six subgroups, with differences mostly due to a different geographical habitat. Sea angels lack the mollusks shell, which explains their scientific name: Gymnosomata (Greek: naked body).

Their body is gelatinous, like that of a jellyfish, and because of its shape, has been referred to being perfectly streamlined for swimming. Their gastropod has developed into a wing-or fin- like extensions, which allows them to perform a rowing or “flying” motion. Evolutionary adaptation on losing the shell and developing fins, unlike on other sea slugs, has given the sea angels the liberty of swimming freely in the oceans. Because of their unique swimming style and highly developed muscles and body shape, sea angels have been the subject to a wide variety of researches in the neurobiology of swimming.

Sea angels are carnivores and adapted in size and behavior to their main prey, sea butterflies or so called sea devils. They catch the butterflies with tentacles located in their mouth. Thus even the largest of sea angels grows only up to 5cm in size. They don’t have eyes, but instead use chemical detectors to find their prey. The chemical detectors are located in the head, looking like horns.

The Antarctic sea angel synthesizes a deterrent, which keeps the predators from eating them. Some other small sea animals use this unique benefit by carrying a sea angel around in order to protect themselves as well. The arctic sea angels have been reported to be found even in densities of 300 to a cubic meter, whereas southern areas densities don’t reach even close. Sea angels have both male and female reproductive organs. They fertilize internally and then release a mass of eggs to float freely until the eggs hatch.

Sea angels have been widely used as visual models in movies and cartoon characters because of their extraordinary looks. In Japan they even sell scientifically designed aquariums for those keeping the delicate arctic sea angels (Clionidae) as pets.