Octopus vulgaris

The common octopus is without doubt the most unique of all marine invertebrates, with its massive bulbous head, large eyes, eight distinctive arms with numerous suckers and no internal shell. 

The most striking characteristic of the octopus is its ability to hide in plain sight. Using a network of pigment cells and specialised muscles in its skin it can almost instantaneously match the colors, patterns and textures of its surroundings. T

he octopus has different techniques in order to avoid or thwart possible predators. It can release a cloud of black ink to obscure their view, giving it time to swim away. Its soft body can squeeze into impossibly small cracks and crevices where predators can't follow since the only hard part of its body is its beak. Another technique is that it can lose an arm in order to escape a predator's grasp and regrow it later with no permanent damage. 

It feeds mainly on crustaceans, but at times when it is unable to find food, it may be forced to eat one of its tentacles in order to survive. This phenomenon is known as autophagy. The female nests and guards the eggs, dying of exhaustion after hatching.

Photo by Theano Dandari 

You can observe octapus in the tanks at the Aquarium of Crete.