DIVE LOG AUSTRALASIA FEB 2026

between the host sponge and its symbionts and those pre-existing that might just arrive via the huge amounts of seawater that sponges are continually filtering. All these toxins and anti-feedants help protect this most simple of animals, the sponge, from a great deal of predation, apart from those animals that have evolved to process the toxic chemicals such as certain species of dorid nudibranchs, some fish and some turtles. Different species of these spongivore nudibranchs have different diets, that is, they only predate on a certain family or genus or even just a single species of sponge. The sponge they eat can depend on the toxic chemicals they have evolved to be able to process. Some nudibranchs that consume

bryozoans, soft corals and ascidians are also known to repurpose the toxic chemicals found within that prey as too, do sacoglossans, sea hares and the herbivorous headshield slugs from their algae diet. Symbiotic bacteria and cyanobacteria, often associated with their food, are also a source of antifeedant compounds. Reference: Rudman, W.B. & Bergquist, P.R. (2007) A review of feeding specificity in the sponge-feeding Chromodorididae (Nudibranchia: Mollusca), Molluscan Research 27(2): 60-88. Next issue: Defensive Glands - Types, Contents and Locations

The Darwinellidae sponge species Chelonaplysilla violacea appears most favoured among certain Goniobranchus . There is a group possessing purple colouration under the anterior mantle and six of these feed upon that sponge. They include these four, Clockwise from upper left: Goniobranchus geometricus; Goniobranchus hintuanenesis; Goniobranchus leopardus; Goniobranchus coi.

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DIVE LOG Australasia #416 February ‘26

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