Threat Display - in Cephalopods

In Cephalopods

Deimatic behaviour is also exhibited by cephalopods including the cuttlefish Sepia officinalis, squid such as Sepioteuthis sepioidea and Sepioteuthis lessoniana, octopuses including Octopus vulgaris and Octopus macropus, and the paper nautilus Argonauta argo. Deimatic cephalopod displays involve suddenly creating bold stripes, often reinforced by stretching out the animal's arms, fins or web to make it look as big and threatening as possible.

For example, in Sepia officinalis, the display consists of flattening the body, making the skin pale, showing a pair of eyespots on the mantle, dark eye rings, and a dark line on the fins, and dilating the pupils of the eyes. Octopus vulgaris similarly displays pale skin and dark eye rings with dilated pupils, but also curls its arms and stretches out the web between the arms as far as possible, and squirts out jets of water. Other octopuses such as O. macropus turn bright brownish red with oval white spots all over in a high contrast display. The paper nautilus rapidly changes its appearance by suddenly withdrawing the shining and iridescent web formed by the first pair of arms from covering its shell.