[1] Current consensus, guided by molecular studies, leans towards interpreting the group as monophyletic.

The two clades may or may not be sister taxa; if not, their similarity (in that they are both pelagic, small, and transparent, and both groups swim using wing-like flaps (parapodia) which protrude from their bodies) may reflect convergent adaptation to their particular lifestyle.

Gray divided the Pteropoda into Dactylobranchia (with just the genus Cavolinia) and Pterobranchia (including all the other genera).

Clark (1829) treated the Pteropoda as a family and emended the spelling to Pteropodidae (a name now re-used for a family of fruit bats) Finally, all these attempts were abandoned and, as more and more species were described as a result of several scientific expeditions, the classification of the Pteropoda into Thecosomata and Gymnosomata was generally adopted.

The oldest known fossil pteropod is a member of Limacinidae from the early-middle Campanian deposits of the San Juan Islands.

[12] This species of pteropod is potentially vulnerable to the corrosive waters associated with ocean acidification due to their calcium carbonate shell.

Continental shelves, areas containing many opportunities for nutrients, and productivity are locations in which Pteropods are usually populous, according to patterns in data.

In addition, current data suggests that 93% of the world's pteropods are part of the Thecosomata family, while the 7% are Gymnosomata.