Body Form of the Vampire Squid:

Vampire squid are small, with a maximum size of 28cm, but more typical sizes are 8cm-13cm. They are bright red, from which they get their name, and are very gelatinous in composition, almost like that of jellyfish. They are more similar to squid in body shape than octopi. The vampire squid have 8 arms with suckers of the distal end and 2 long, retractible sensory tentacles, known as velar filaments. Between the arms there is extensive membranous webbing which is black on the underside, and two pouches in the webbing can conceal the velar filaments. On the underside of the webbing and arms are spike-like projections called cirri, but they are as soft as the rest of the organism. They have very large eyes and perhaps the largest eye to body ratio in the animal kingdom.

The webbing and cirri associated with the arms of a Vampire Squid.

The have two fins towards the apex of the mantle. These fins are responsible for the primary locomotion in these animals. These fins are not entirely homologous to squid fins in a similar position. Juvenile Vampire Squid have a pair of fins close to the apex of the mantle, and these are homologous to squid fins, but as it matures it undergoes a metamorphosis. A second pair of fins are produced behind the first and the first pair are re-absorbed. Therefore, there is a stage in development in which vampire squid have 4 fins, and this lead to early confusion in regards to number of species of Vampire Squid.

A juvenile Vampire Squid undergoing metamorphosis - this is the 4-fin stage.

Vampire Squid have poorly developed chromatophores and is unable to produce the complex colour changes of squid and cuttlefish. They also lack ink sacs. As they live in deep, dark environments, they instead have complex photophores for display (ie: to scare predators or attract prey). These photophores are located on the tips of each arm as well as at the base of the fins. Additionally, clouds of glowing particles can be ejected from the tips of the arms, functioning similarly to ink in squid (to startle a predator that has come too close). The control of the photophores is finely tuned – the length of the display can be very short or sustained and the intensity of the display can also be controlled. These photophores are involved in complex displays which I will discuss later.