These results fit the ‘risk allocation’ hypothesis (Lima and Bednekoff, 1999). O. vulgaris is known to be a common food staple for eels ( Hanlon and Messenger, 1996), while it is rather rare in the diet of a triggerfish. The moray would therefore represent a far too frequent risk to respond to by switching the activity cycle. Nonetheless, in our study, the octopuses responded with expected shorter, more frequent bouts of activity. Animals that are incidental prey to a generalist predator are most likely to benefit from a shift in activity timing, while a predator that specializes in a particular prey species will most likely match any change in the prey's activity pattern ( Lima and Bednekoff, 1999 and Lima et al., 2005).