Where do sea angels live?

Sea angels previously known as one kind of pteropod, are a large group of small swimming sea slugs in six different families. These are pelagic marine opisthobranch gastropod molluscs in the clade Gymnosomata within the larger clade Heterobranchia.

Sea angels are also sometimes known as "cliones", but this is potentially misleading because the family Clionidae is just one of the families within this clade.

Recent molecular data suggests that the gymnosomata form a sister group to the Thecosomata, other planktonic, weakly or non-mineralized gastropods, although this long-standing hypothesis has had some recent detractors.[1]