tahiticrabs's Identifications

A pair of the small coral crab Tetralia cf. ferruginea, was found in a colony of the coral Pocillopora damicornis at Sesoko Island, Okinawa, Japan. The male is on the left, and the larger female on the right.

My M.S. advisor, Dr. Makoto Tsuchiya, studied the behavior of this and related crabs and shrimps that are obligate symbionts on some corals, including other species of Porites and Acropora corals.

These coral crabs are amazing; they live on the coral, among its branches. Some in situ observations (by colleagues) suggest that these crabs defend the coral colony from the large predator Crown-of-Thorns Starfish, Acanthaster planci, by pinching the starfish tube feet. It may provide some protection to the coral, but if the starfish is hungry, say, because there are few live coral in the area, the crab may not succeed.

Photo taken in the lab at the University of the Ryukyus, Okinawa, of specimens collected in the wild. The scale in millimeters. (the watermark is when I posted this photo at the now defunct website LightBox, not the observation; the exact date of observation is not know).

I wrote a paper on the species composition and population traits of these coral crabs, presented at the 7th International Coral Reef Symposium, Guam, 1992, and published in its proceedings in 1994. Let me know if you want a copy of the paper (you can email me at mollusca at gmail.com).