Limacina helicina

Limacina helicina is a species of small swimming planktonic sea snail, in the family Limacinidae. It belongs to the group commonly known as sea butterflies (Thecosomata).

Limacina helicina is a keystone species of mesozooplankton in Arctic pelagic ecosystems.

The first written record of this species was by Friderich Martens from Spitsbergen in 1675. Limacina helicina was also observed during a 1773 expedition to the Arctic led by Constantine John Phipps on the ships HMS Racehorse and on HMS Carcass and the species was described one year later, in 1774.

Limacina helicina is the type species of the genus Limacina.

In contrast to the traditional view, it was shown in 2010 that the distribution of this species is not bipolar; Arctic and Antarctic individuals belong to two genetically distinct species: Limacina helicina in the Arctic, and Limacina antarctica in the Antarctic.