Body
Body and tentacles usually up to 500mm long, armspan 700mm; extreme maximum body & tentacle length 660mm [image 1]. Mantle an oval bag [2], fused with head dorsally; mantle aperture ventral with exhalent respiratory funnel which can be extended at varying angles. Surface can be varied from smooth [3] to tuberculate [14] , but not pronounced lobes. No fins. Ventral surface white [1], hence Spanish and French vernacular names “blanco”, “blanche”; clearly demarcated from dorsum by pale rim around lateral periphery of mantle [5]. Dorsal surfaces of mantle, head and arms usually terracotta to orange-red [6], sometimes with white patches, and, when agitated, mobile red blotches [7].
Head
Large, highly-developed eyes [8] usually positioned laterally [4] with substantial rim which can be lowered. Pupils are horizontal slits, so slit aperture permits good vision [4], though aperture can be opened wide [3].
Arms
Eight equal arms. Each arm has one rows of suckers [9] but, on slender tips, sometimes deflect alternately to right and left to give almost double row effect [10]. Arms linked basally by web [11].
Internal hard parts
Ancestral internal shell reduced to slender flexible “bones” [13]. Chitinous “parrot’s-beak” at base of arms [11] & [12].
Octopus vulgaris Cuvier,1797
Usually sublittoral to 120m. Mainly benthic, moving on arms, but jet propels water from exhalent funnel for rapid escape [5]. When threatened, can eject distracting ink before jetting away. Predators include seals and man. Crabs and lobsters eaten, including those in lobster pots. Vestigial skeleton enables it to squeeze through gaps no wider than its beak. Up to 60 eggs laid. Young hatch as miniature adults and drift in plankton for a time.
From Norway and Iceland to Mediterranean. Commonest in northern part of distribution; pest species for lobster fishermen in Orkney. (GBIF map) . Some northern records of Octopus vulgaris may be misidentified Eledone cirrhosa. Many records in seas all round Britain, except few along E & S coasts from Whitby to Torquay. UK interactive distribution map, (NBN).