Spatial distribution of turtle barnacles on the green sea turtle, Chelonia mydas

Distribution patterns of epibiotic barnacles on green sea turtles were investigated in waters neighboring Okinawa, Japan. A number of barnacle species were found to coexist on the turtles and were classified into three genera: Chelonibia, Platylepas and Stomatolepas. Attachment sites on the turtles varied among the barnacle species, suggesting that there is niche partitioning with respect to their microhabitat selection. Turtle bodies offer a “patchy” environment for barnacles, so we also analyzed coexistence patterns in the context of an aggregation model. Within each genus, individual barnacles showed a clumped distribution. The different genera do not have mutually exclusive distribution patterns, but instead occur on the same turtle to various degrees. However, when turtles were divided into two size classes, both the level of aggregation and the degree of interspecific overlap among the barnacles was significantly lower on large turtles. We suggest that obtaining basic information on turtle epibionts will shed light on the biology of wild turtles, which is still largely unknown.