Giant Bumphead Parrotfish are Violent Headbutters
Posted on June 12, 2012
U.S. researchers have discovered that bumphead parrotfish (Bolbometopon muricatum), a giant reef fish, holding violent headbutting contests. The large fish can reach nearly 5 feet in length and weigh up to 75 kilograms (165 pounds). The headbutting behavior was observed in the coral reefs of Wake Atoll. The researchers say they heard loud jarring sounds and confirmed they arose from violent impacts between Bolbometopon males engaged in repeated, ritualized headbutting behavior. The research was published here in PLoS One.
The researchers say male bumphead parrotfish "use their caudal fins to rapidly collide with their cephalic humps." This was "immediately followed by fast swimming in a semicircle where each fish tried to bite the back and flank of its opponent. Following circling, fish swam apart in opposite directions and then turned again face to face to initiate additional collisions."
The researchers make comparisons of the Bolbometopon headbutting to male bighorn sheep horn battles in the research paper. The researchers say, "Bolbometopon males exhibit what appears to be an 'ossified ridge' on the forehead that may serve a similar function as the cranial appendages of artiodactyls."
Nature reports that the aggressive headbutting has never been spotted before in the species. Take a look: