Crustaceans in Acropora

Botanic gardens library is still selling a 1994 book on Labrador Rhythm Of The Sea - The Life And Times Of Labrador Beach. Though the book is quite dated, it's still a great book for its price of $15. It has in it among other things, the ID of the crustaceans we see in Acropora coral.


Kok Sheng first spotted these crabs on one of our southern shores (photo by Kok Sheng).


I have also seen them on Kusu.

The crabs are white coral crabs (Tetralia nigrolineata), only found on Acropora coral and feed on the mucus produced by the coral polyps which they gather using minute comb-like structures on the tips of their feet. They are also known to defend the coral from predators like the crown-of-thorns by pinching the tube feet of the sea star.



This shrimp is known as the machinegun shrimp (Coralliocaris graminea), also only found on Acropora coral. It can snap its claws in a similar fashion to snapping shrimp except it can snap both claws, sometimes alternately in quick succession which is the reason behind its common name. This shrimp also feeds on the mucus produced by the coral polyps and believed to possibly also defend the coral from predators. A complete photo of it can be found here.