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Spanish Dancer, Hexabranchus sanguineus Spanish Dancer, Hexabranchus sanguineus
Spanish Dancer
(Hexabranchus sanguineus)
This is one of the larger nudibranchs seen at Julian Rocks and it has six gills on its back. Once you have seen this nudibranch swimming it is clear where its common name comes from as it mantle margins wave up and down like the skirts of a Spanish Dancer.
The egg ribbons (photo on the right) are very easily recognised by the pink/orangy colouring.

Note: please don't try and pull this nudibranch off the substrate it is resting on in order to make it swim as you can injure or even kill it by doing so.