Grimpoteuthidae are a family of bentho-pelagic octopuses, comprising three currently accepted genera. They have extensive arm webbing and relatively large fins allowing for powerful fin swimming.
Description
Grimpoteuthidae have a strongly U-, V-, W-shaped internal shell (gladius remnant) that supports muscles for large fins. These fins are proportionally much larger than in the related Opisthoteuthidae, and allow for much stronger swimming using the fins alone (unlike Opisthoteuthids that mostly use the arm webbing for swimming). Unlike Cirroctopodidae and Opisthoteuthidae, Grimpoteuthids also have the optic nerves heading to each eye as a single bundle (in the other families this occurs as multiple separated nerve bundles). The extensive arm webbing is shared with Opisthoteuthidae and Cirroctopodidae.
Taxonomy
The following genera and 19 species are currently accepted in this family. The family has consistently been supported in molecular studies as distinct from Opisthoteuthidae and Cirroctopodidae. Many species in the family are known from only a handful (or even single) specimens, and the taxonomy within the family is very uncertain with many species in Grimpoteuthis possibly being representatives of Cryptoteuthis or even new genera.