Predators & defenses
   
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  Defenses
   
 

Withdrawal & inking
   
  Defenses of octopuses and their relatives can be divided into passive and active. Topics relating to passive defenses include , HIDING AWAY, NOCTURNAL BEHAVIOUR, COLOUR CHANGE/CAMOUFLAGE, and MAKE BODY SEEM LARGER, considered in other sections.  Active defenses include withdrawal & inking, considered here, and BEAKS & BITING, considered in another section. 
 
Research study 1
 

There are many potential predators of west-coast octopuses. For example, of 39 octopuses Enteroctopus dolfleini collected in the Clayoquot region of British Columbia, 19 are found to have missing or partly missing arms and 26 have scar damage.  Little is known, however, of which predator from a long list of potential ones is actually most important, or whether inking acts to protect against attacks by large predators such as seals, sea lions, and other mammals, let alone from attacks by large fishes and sharks. Hartwick et al. 1978 J Fish Res Bd Can 35: 1492.
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photograph of a Humboldt squid stranded and moribund releasing ink

CLICK HERE to see a video of ink release in a stranded and moribund Humboldt squid Dosidicus gigas.

NOTE the video replays automatically
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In the absence of of any specific studies on function of inking and withdrawal in defense of west-coast octopuses, consider what potential functions may be served by inking from the following list, then CLICK HERE for explanations.

The ink acts to hide or obscure the intended prey from the predator.

The ink acts as a dummy or decoy to distract the predator.

The ink acts to anaesthetise the predator's sensory perception.

 
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