The green humphead parrotfish, Bolbometopon muricatum, is a four foot coral-chowing bulldozer that can weigh up to a hundred and fifty pounds (70 Kg). There are many different species of reef fish that have humps and protuberances of some kind but the humps of Bolbometopon parrotfish are especially large and bony, especially the males. No one ever knew what the large bony humphead was for but a brand new video shows the humphead parrotfish doing what intuition would lead you to believe. Like large horned and humpheaded four legged beasts, the male humphead parrotfish use their bony head plate to ram each other in territorial disputes.
As the video shows, the large male green humphead parrotfish ram each other in an explosive display of power that makes a loud cracking sound underwater. We can imagine that if the sound of shrimp clicking, clacking and snapping is saturating while diving, the sound of two large males ramming their humpheads has to be feel like a thunderous clap, maybe even a palpable shockwave. Since green humphead parrotfish are such large and conspicuous fish on the reef, it’s a wonder that the ramming behavior has never been documented until now, the first such case for any reef fish. Perhaps future research and observation will explain a little more about when and why green humphead parrotfish have ramming contests. [sci-news]