The "Little Cuttlefish", Sepiola atlantica. Also known as the Atlantic Bobtail, it is a species of bobtail squid native to the northeastern Atlantic Ocean (65N to 35N), from Iceland, the Faroe Islands and western Norway to the Moroccan coast.
This species differs from the giant cuttle and mourning cuttle in it's reddish blotched colouration (although this one changed colour several times whilst being photographed), relatively round body and eyes with a smooth socket and yellow edge. The mourning cuttle has a long mantle that extends between the eyes, and the giant cuttle has skin flaps on it's body and behind the eyes.
Cuttlefish, like their cousin the octopus, have eight arms. Cuttlefish differ however in that they have in internal calcareous "shell" that is porous; they use this for buoyancy control in order to hover level. Their movement is largely controlled by fluttering fins along the side of their body. They also have two specialised tentacles; they can shoot them out to grasp their prey.
The red cuttle is not always red - this series of shots shows the one individual as it changes colour from dark red to lighter mauve. This is one of three cuttle species in Australia; the yellow lining around the eye is diagnostic of the species.Camera settings including strobe are identical for all three shots.