DIVE LOG AUSTRALASIA FEB 2026

STAYIN ALIVE THE DEFENCES OF SEA SLUGS - Part 6 Passive Defences continued

Chemical Defences The employment of chemical compounds by sea slugs as a defensive means is integral in both passive and reactive methods. It could be considered the single most important means of self protection in dorid nudibranchs and is believed to be utilized, in one form or another, by all sea slug taxons, often in conjunction with other methods, in varying degrees of complexity.

The sea is a soup of chemicals, so sea slugs live in an environment that revolves around chemical compounds for two-way communication – incoming and outgoing – for the functioning of feeding, protection and reproduction. We only have to look at the major sensory organ of sea slugs, the rhinophores or their equivalents, designed to detect chemical cues in their fluid environment, at a distance from their release location, to appreciate

Clockwise from upper left: Sponges, ascidians, bryozoans and algae - these are the major food sources of the dorids, sacoglossans and sea hares. All of these food sources contain secondary metabolites or antifeedants to prevent predation or grazing. Sea slugs have evolved ways and means to overcome, neutralise or to even repurpose those toxic substances, often species specific. DIVE LOG Australasia #416 February ‘26 20 www.divelog.net.au