Colour in sea slugs

Dear Austin,
Most of the information on opisthobranch colour is on one page Defence - Colour patterns. Have a look there as it links to many different ways that colour is used by sea slugs, and also the different ways they obtain their colour.

Many do obtain their colour from external sources. Many of the sacoglossans, like Stiliger smaragdinus, get their colouring from the algal pigments they ingest, and the nudibranchs which retain unicellular plants (zooxanthellae) are coloured by those plants. Others, like most species of Rostanga, including Rostanga arbutus and Rostanga bifurcata take the red pigments from their sponge food and incorporate in their skins, and apparently their eggs as well.

Despite this widespread reliance on other plant and animal pigments, the majority of opisthobranchs manufacture their own pigments. A good example of this is the chromodorids which apparently generate the pigments which make their spectacular colour patterns.

Best wishes,
Bill Rudman.