DIVE LOG AUSTRALASIA ISSUE 413 AUGUST 25

Above: A small selection of dorid nudibranchs, across three genera, illustrating a range of presentations that exhibit aposematism . Bold, often contrasting colours and eye-catching patterns are actually designed to attract attention and serve to warn potential predators of their toxic/distasteful nature. This warning is of benefit to both predator and prey. Clockwise from upper left: Ceratosoma amoenum, Goniobranchus coi, Hypselodoris variobranchia and Ardeadoris rubroannulata - so many different colours and so many different arrangements.

Mimicry by congeners Mimicry by congeners is a complex subject. Here we are concerned with sea slug species visually mimicking one another for defensive purposes rather than items or food sources in the habitat or unrelated animals. Mimicry is not a conscious effort by a species to look like another. It is an evolved resemblance that has come about through selective pressure in the habitat. It is the success of those evolved changes in that habitat that sustains the mimic. The mimic is successful because it gains a

survival advantage usually in that its appearance serves to warn a predator that it may be noxious or distasteful, just like its model. The mimic may itself be noxious or not. Essentially it is also about sharing the load of “teaching” predators to avoid them. Mimicry in sea slugs is of a defensive not an aggressive nature and there are a number of categories but two are of particular significance: Batesian and Mullerian. These two categories will be explained in the next issue.

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DIVE LOG Australasia #413 -August ‘25

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