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Size – They are extremely small with the largest (Clione limacina) reaching just 3inches (7-8cm) in size.

Sea Angels are very small, transparent, and gelatinous swimming sea slugs. Many compare them to jellyfish and other similar creatures, but they are indeed Gastropods. They are unique due to their wing-like appendages and lack of shell. These beauties are able to flap their wings and move at a speed of .22mph/s (100mm/s.)

These organisms have a wide geographic range, from polar regions, under sea ice, to equatorial (tropic) seas. The largest, the Clione limacina, is most often found in the cold waters of the Arctic at depths of 1,600ft (500 m.)

They have an interesting relationship with their fellow pteropods, Sea Butterflies, who are the only source of food the Sea Angels consume. There are differences in feeding/hunting approach among the Sea Angels. Some ambush, while some simply actively pursue and hunt.

To move, Gymnosomata slowly flap their wings, similar to a rowing motion, in order to move their bodies through the sea. Although they are fairly slow moving, they are capable of bursts of speed when actively hunting a Sea Butterfly. Their life span appears to be just 2 years.

Sea Angels belong to the clade Gymnosomata. This is a large group of these extremely small swimming angel slugs. Their name is derived from the Greek meanings of the words Gymnos and Soma. This translates to “Naked body.”

The clade is arranged with six families across two super families:

  • family Clionidae
  • family Cliopsidae
  • family Notobranchaeidae
  • family Pneumodermatidae
Sea Angel Photo 1
By רפאל גורי - I did this photo, CC BY-SA 3.0,
Sea Angel Photo 2
By Matt Wilson/Jay Clark, NOAA NMFS AFSC - NOAA Photo Library, Public Domain,
Sea Angel
"Sea Angel" by Prue_T is licensed under CC BY-NC-ND 2.0.