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Predators & defenses |
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Defenses |
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Colour change
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Defenses of octopuses and their relatives can be divided into passive and active. Topics relating to passive defenses include colour change, considered in this section, and HIDING AWAY, NOCTURNAL BEHAVIOUR and MAKE BODY SEEM LARGER, considered in other sections. Active defenses include BEAKS & BITING and WITHDRAWAL & INKING.
Colours in cephalopods result from contraction and expansion of chromatophores, or colour cells, scattered within the skin. In cephalopods the chromatophores are under nervous control; hence, colour changes are virtually instantaneous. In comparison, chromatophores in
fishes and crustaceans are under hormonal control and responses are slower - measured in minutes, hours, or days. |
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Research study 1 |
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 Abrupt colour changes including blanching are common responses to distubance or stress in octopuses. They may be accompanied by escape by crawling and jetting, and by ink release.  Additionally, when an octopus is in defensive attitude, the arms may curl around on themselves (see model on Right) while the chromatophores rapidly change colour. Mather 1998 J Comp Psychol 112: 306.
Enteroctopus dolfleini in
partially blanched mod |
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CLICK HERE to see a short video of an octopus Enteroctopus dolfleini exhibiting quick colour change.
NOTE the video replays automatically |
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Research study 2 |
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Detailed studies of colours and patterning in Octopus bimaculoides in southern California disclose 8 general colour patterns. These are:
 1 & 2. UNIFORM LIGHT & GENERAL MOTTLED: these common or "chronic" patterns are used for concealment and persist for a long time. In comparison, the next 6 “acute” patterns last only seconds or minutes, and are used for localised encounters involving sex, aggression, and the like.
3. UNIFORM DARK & ACUTE MOTTLED
4. DISRUPTIVE: in hatchlings the body is divided into dark halves separated by a longitudinal whiteish central stripe. Variations of pattern are used for concealment.
5. DEIMATIC ("god-like" L.): a mottled pattern accompanied by well-defined ocelli.
6. FLAMBOYANT: an uncommon behaviour seen in small swimming individuals; accompanied by raised skin papillae.
7. PASSING CLOUD: waves of chromatophore expansions radiating from arm bases to tips; seen in young animals. Forsythe & Hanlon 1988 Malacologia 29: 41. Photograph of O. bimaculoides above and the 2 Right-hand eyspots below courtesy Roger Hanlon, Woods Hole Marine Biological Laboratory, Woods Hole, Massachusetts.
Rapidly moving O. bimaculoides displaying No. 1 colour pattern
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Other than general pattern disruption and camouflage, the function of colour patterns in O. bimaculoides and octopuses, in general, are not well understood. In addition, in adult O. bimaculoides there are 2 or more prominent white spots on the mantle, and 2 prominent eyespots or ocelli symmetrically placed on the upper arm web. The spots are usually brilliant blue on a variable background, but colours vary depending upon age and behaviour. Their function is unknown.
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From L to R: juvenile, dark-coloured adult, light-coloured adult |
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CLICK HERE to see a video of chromatophore activity in a Humboldt squid Dosidicus gigas. This individual has been stranded on the beach for several hours and is nearly dead. What you see is a rapid flickering as chromatophores in the mantle skin expand and contract.
NOTE the video replays automatically |
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