Predators & defenses
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  Defenses
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Nocturnal behaviour

   
 

Defenses of octopuses and their relatives can be divided into passive and active. Topics relating to passive defenses include nocturnal behaviour, considered in this section, and HIDING AWAY, COLOUR CHANGE/CAMOUFLAGE, and MAKE BODY SEEM LARGER, considered in other sections.  Active defenses include BEAKS & BITING and WITHDRAWAL & INKING

Nocturnal behaviour in octopuses is thought to be of adaptive value in keeping them out of sight of visual predators.

 
Research study 1
 

photograph of octopus Enteroctopus dolfleini crawling in a tankThe largest species of west-coast octopus Enteroctopus dofleini is usually thought to be nocturnal. However, sonically “taggedEnteroctopus dofleini, monitored continuously throughout successive 24-h periods, show general activity throughout the 24-h day (see graph on Right). There is slight peak in activity from 2100-0200h, and a depression in activity from 1500-1700h, but the idea that this species is strictly nocturnal appears not to be true.  Trips from the home den presumed to involve hunting are frequent, average about 0.5h in duration, and are generally greater than 20m from from the den. Night trips are longer, averaging 1.5h. Mather et al.1985 Mar Behav Physiol 11: 301.

NOTE  a description of the sonic devices and methodology can be found elsewhere in the ODYSSEY: LEARN ABOUT OCTOPUSES & RELATIVES: HABITAT ECOLOGY: ENTEROCTOPUS. The data shown in the above graph are repeated from this other section

NOTE  the studies are done in summer when daylight lasts for 14h

 
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