Common Octopus

Octopus vulgaris

Common Octopus (Octopus vulgaris) is a species in the genus Octopus, family Octopodidae, order Octopoda.

Scientific classification

Description

The common octopus is a soft-bodied cephalopod with eight arms, each bearing two rows of suckers, and no skeleton apart from a small cartilaginous braincase and a horny beak. Because the beak is the only rigid structure, an octopus can pass through any opening the beak will fit through.

Colour and texture are under direct nervous control. Chromatophores — pigment sacs opened and closed by radial muscles — sit above reflective iridophores and leucophores, allowing changes of pattern in well under a second, together with papillae that alter the skin's three-dimensional texture. The animal is, as far as is known, colourblind, so the mechanism by which it matches its background remains an open question; light sensing in the skin itself has been proposed.

Nervous system

Roughly two thirds of the neurons lie in the arms rather than the central brain, and an isolated arm will still perform coordinated reaching. Octopuses learn by observation, solve mazes, open jars, navigate by landmarks, and show individually consistent behavioural differences. Their nervous system is the most complex known outside the vertebrates and evolved entirely independently of ours, which makes them the standard comparison case for asking what intelligence requires.

Life history

Short-lived — typically one to two years. Reproduction is terminal: the female seals herself in a den, tends her eggs continuously without feeding, and dies around the time they hatch. Males die some months after mating.

References

• Godfrey-Smith, P. (2016). Other Minds: The Octopus and the Evolution of Intelligent Life.
• Hanlon, R. T. and Messenger, J. B. (2018). Cephalopod Behaviour, 2nd edition.