The cephalopods (meaning ‘head-footed) are a group of molluscs that contain the octopuses, squid and cuttlefish, and are probably the most intelligent of all invertebrates. They have well-developed heads, with large complex eyes and mouths that feature beak-like jaws. All octopuses have eight tentacle-like arms; indeed ‘octopus’ derives from the Greek for ‘eight-footed’ (3). The common octopus usually measures around 60 centimetres in length, but it can grow up to 1 metre (2). It is able to change its colour depending on its mood and situation, but individuals are usually greyish-yellow or brownish-green with extensive mottling. They are often very well camouflaged (2). The body is warty, and the thick arms bear two rows of suckers (4).
Like all cephalopods, the common octopus is an intelligent active predator (4). They have modified salivary glands that produce venom used to incapacitate prey. It is often easy to identify what a common octopus has been feeding on, as they leave piles of debris known as ‘middens’ around the entrance of the protective lair in which they live. These middens consist of debris from a range of species and often include mollusc shells and the carapaces of crabs and other crustaceans(5).
All cephalopods are good swimmers, and are able to move rapidly by jet propulsion when threatened; water is rapidly expelled through a funnel which causes the octopus to be propelled away rapidly (3). Cephalopods are also able to mask themselves as they escape with a cloud of ink released into the water (2).
This octopus is found from the southern North Sea down to South Africa. It also occurs in the Mediterranean (2). It reaches the north-eastern extreme of its range in Britain where it is found only around the coasts of the south and south west (4).
The top shell of a turtle. In arthropods (insects, crabs etc), the fused head and thorax (the part of the body located near the head) also known as ‘cephalothorax’.
Diverse group of arthropods (a phylum of animals with jointed limbs and a hard chitinous exoskeleton) characterised by the possession of two pairs of antennae, one pair of mandibles (parts of the mouthparts used for handling and processing food) and two pairs of maxillae (appendages used in eating, which are located behind the mandibles). Includes crabs, lobsters, shrimps, slaters, woodlice and barnacles.
A marine zone between the littoral zone (the shallow zone where light reaches the bed, subject to submersion and exposure by tides) and depths of around 200m.
Gibson, R., Hextall, B. and Rogers, A. (2001) Photographic Guide to the Sea & Shore Life of Britain and North-west Europe. Oxford University Press, Oxford.
Buczacki, S. (2002) Fauna Britannica. Hamlyn, London.
Wilson, E. (1999) Octopus vulgaris. Common octopus. Marine Life Information Network: Biology and Sensitivity Key Information Sub-programme. [On-line]. Plymouth: Marine Biological Association of the United Kingdom. (November, 2003) http://www.marlin.ac.uk/species/Octopusvulgaris.htm
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