shrimp, sea anemone, symbiosis, diversity

Giant sea anemones in the Red Sea (5 species) and Caribbean Sea (2 species) both hosted diverse assemblages of anemoneshrimps (6 and 5 species respectively). In each region, members of one anemoneshrimp species (Periclimenes longicarpus in the Red Sea and P. pedersoni in the Caribbean) formed social groups of up to 10-14 individuals per anemone in about 30-50% of host individuals, and served as major cleaners of fishes. Two other members of the genus Periclimenes (P. brevicarpalis and P. ornatus) occurred singly or as mated pairs in 9-13% of host anemones in the Red Sea, while individuals of P. yucatanicus in the Caribbean Sea exhibited a similar pattern.. One species of anemoneshrimp, Thor amboinensis, occurred in both regions but formed larger social groups (up to 90%) in the Red Sea than in the Caribbean Sea (only 2%). Unique to the Caribbean Sea was association between anemones and alpheid snapping shrimps (Alpheus armatus group), which occurred in about 35% of host individuals.