Risbecia tryoni (Garrett, 1873)

Risbecia tryoni is found occasionally at Enewetak and Kwajalein Atolls. The best place for them was on the pilings under Medren Island pier at Enewetak until the summer storm of 1982, when the southwesterly swell generated by the storm washed them all away. It took about 8 months, but they finally started to show up under the pier again in March of 1983. Aside from the pier, they can be found occasionally on lagoon pinnacles and along the interisland subtidal reefs at depths of about 2 to 12 meters. Specimens we've seen have ranged from 5 to 70mm in length.

This species, like others in the genus Risbecia, will often queue up to move along the reef. Most commonly, this is referred to as trailing behavior, although I kind of like an alternate term, "queuing behavior." In queuing, the following individual crawls along immediately after the leader, with the anterior edge of its foot on the leader's tail. Although usually paired, occasionally you can see three in a line as shown in the lower photo below.

Created 3 January 2006
Updated 4 January 2009