‘Preener’
Mithraculus cinctimanus crab on Ricordea florida corallimorphs
Music, Video, and Aquarium
2010 Coral Morphologic

Shown above is a 1cm Mithraculus cinctimanus, commonly known as the banded clinging crab. Typically this species is known to live in association with a variety of Caribbean sea anemone species. However, several years ago we noticed that juvenile and sub-adult banded clinging crabs seemed to prefer the protection amongst Ricordea florida polyps in the wild. When they are small, like this one, the carapace (shell) of the crab is nearly entirely covered by a fuzzy red algal camouflage. As they get larger (up to 25mm) they lose much of this hairy coat, revealing a striking white and maroon patterned exoskeleton.

The video shows the crab alternating between preening its own algae covered carapace and the fluorescent tentacles of the Ricordea florida on which it lives. It is possible that the crab may ingest some of the polyps’ mucus as an occasional food source. The video was sped up considerably (9x). At normal speed the polyps appear static, but at this speed the regular hydraulic undulations and contractions of the R. florida polyps are clearly visible.