Lebensspuren von Upogebia operculata (Crustacea, Decapoda) in karibischen Steinkorallen (Madreporaria, Anthozoa) [Traces of Upogebia operculata (Crustacea, Decapoda) in Caribbean stony corals (Madreporaria, Anthozoa)]

The thalassinid shrimp Upogebia operculata SCHMITT (1924) inhabits several spe cies of massive stone corals from various reef sites at St. Croix, U. S. Virgin Islands, in the Caribbean. The animals and in particular their lebensspuren are illustrated for the first time. Eight examples of such burrows (some from Upogebia sp. from the Great Barrier Reef off Australia) are presented. They are excavated by using the claws. For the individual shapes in burrows, structural differences in coral skeleton, growth form and size seem to be most important. Socalled turning chambers arc missing. Due to the short length of the carapax, being less than the burrow diameter, somersaults can be performed almost anywhere by the shrimps, which live in pairs. Certain parts of the burrows, where the shrimps seem to be during active filter feeding, are particularly well mud lined, matching exactly the width of the circular operculum. New and eroded old burrows in single corals indicate a life span of some years for U. operculata and their ability to react to changes in the spatial relation ship between burrow and substratum in advance and in time. In comparison to sand and mud. ad vantages for a life in hard substratum are seen in its higher durability, lesser necessary maintenance, and better shelter from predators. Thus the high expenditure of energy for establishing the dwell ings may be compensated.