Cephalopod fin

Standard measurements for squid, showing the location of the fins and tail in different configurations
Measurement of fin angle in a squid with sagittate fins

Cephalopod fins, sometimes known as wings,[1] are paired flap-like locomotory appendages. They are found in ten-limbed cephalopods (including squid, bobtail squid, cuttlefish, and Spirula) as well as in the eight-limbed cirrate octopuses and vampire squid. Many extinct cephalopod groups also possessed fins. Nautiluses and the more familiar incirrate octopuses lack swimming fins. An extreme development of the cephalopod fin is seen in the bigfin squid of the family Magnapinnidae.[2]

Fins project from the mantle and are often positioned dorsally. In most cephalopods, the fins are restricted to the posterior end of the mantle, but in cuttlefish and some squid they span the mantle's entire length.

Fin attachment varies greatly among cephalopods, though in all cases it involves specialised fin cartilage (which reaches its greatest development in Octopodiformes).[3] A fin may be attached to the internal shell or shell remnant (such as the gladius), to the opposite fin, to the mantle, or a combination of these.[4]

Time series showing up-and-down fin movement in an individual of the cirrate octopod Cirroteuthis muelleri
  1. ^ Young, R.E., M. Vecchione & K.M. Mangold (1999). Cephalopoda Glossary. Tree of Life Web Project.
  2. ^ Vecchione, M. & R.E. Young (1998). The Magnapinnidae, a newly discovered family of oceanic squid (Cephalopoda: Oegopsida). South African Journal of Marine Science 20(1): 429–437. doi:10.2989/025776198784126340
  3. ^ Young, R.E., M. Vecchione & K.M. Mangold (2000). Cephalopoda Fin Cartilage. Tree of Life Web Project.
  4. ^ Young, R.E., M. Vecchione & K.M. Mangold (2001). Cephalopod Fin Attachment. Tree of Life Web Project.