Caracanthus unipinna - Pygmy Coral Croucher  and

Caracanthis maculates - Spotted Coral Croucher

Caranthis unipinna, the Pygmy Coral Croucher, is easily overlooked within the branches of coral, and that is part of its plan. Looking like a harmless blob, this fish wedges itself between coral branches in the depths of the corals, preying on other coral-dwellers who come for shelter. It’s covered with papillae, giving it a fuzzy appearance and a sponge disguise, but with venomous dorsal fin spines nothing about this fish is warm or soft. They can however, be nice to each other – males and females form monogamous pairs, and small groups of crouchers develop what may be complex social interactions within the depths of host corals. They are true to their corals, and once settled into one, spend the rest of their lives in that same coral head.

Caranthis maculates, the Spotted Coral Croucher, is the good-looking, friendly cousin of the Pygmy Coral Croucher. It is light grey/tan in color with reddish spots, and its body is covered with papillae, giving it a furry appearance similar to C. unipinna. Like the other Coral Crouchers, it lives down in the depths of its host corals, eating unsuspecting invertebrates that venture into the coral branches. Because species of Caranthis are hard to see, we know little about the ecology of these fishes, and the role they play on the reef - we think that they play an important role in regulating densities of coral-associated organisms. Despite all that is unknown about Caranthis, one thing is certain: When we peer into a coral head, whether we seem them or not, Crouchers are in there looking back out at us!

Read the National Geographic Feature issue on Moorea BioCode, March, 2011.