ABSTRACT. Barnacles are sessile organisms that attach themselves permanently to the surface of hard or living substrates. Marine turtles are one example of living substrates colonised by barnacles. A survey was conducted from August 2010 to February 2011 to observe the barnacles on resident green (Chelonia mydas) and hawksbill turtles (Eretmochelys imbricata) of Mabul and Sipadan Islands, located on the East Coast of Sabah. This survey intended to produce a list of barnacle species occurring on turtles in these islands and the specific location of the barnacles on the bodies of turtles. One barnacle species, Chelonibia testudinaria (diameter 20.11 ± 8.15 mm from 291 specimens) was identified from 64 turtles – 2 hawksbills and 62 greens. The colonisation site for most of the barnacles was on the plastron of the turtles. From the observation in present study, turtles were cleaned by dusky surgeonfish, Acanthurus nigrofuscus and striated surgeonfish, Ctenochaetus striatus in two dive sites (Staghorn Crest and Barracuda Point) of Sipadan Island. Turtles inhabit and forage near to these turtles cleaning stations consequently having smaller number of barnacles while turtles inhabiting non-cleaning station environments have larger numbers of barnacles.
KEYWORDS. Turtles, barnacles, surgeonfish, Mabul, Sipadan