Ringed sap-sucking slug

On one of our trips last year, I came across this tiny slug which we have not seen in Singapore before!


With the help of Chay Hoon's identification, we found out that it is the Ringed sap-sucking slug (Plakobranchus sp.).

Why are they called the sap-sucking slugs? These slugs are known to feed by sucking the cell sap out of algae. Some species of the Plakobranchus genus keep the chloroplasts from the algae alive in their own bodies for photosynthesis by storing huge numbers of bright green chloroplasts in ridges hidden from view beneath their flaps.

But why beneath their flaps and not above to capture sunlight and make food? Read here to find out more about Dr Bill Rudman's interesting hypothesis that Plakobranchus deliberately shades the chloroplasts from the bright tropical sun.


Here's the underside of the slug with a tail that is bright blue in colour.


Initially it was hard to spot them because they remain very much well camouflaged with the sand when they are semi-buried. Haha. Actually they are quite a number of them but it takes a keen eye to spot them.