Scientists diving in the North Pacific were jarred when they heard mysterious sounds like spear guns being fired. The jolting noises turned out to be never-before-seen (or heard) head-butting bouts between some of the largest coral-reef fish, called parrotfish.
As they studied groups of the giant bumphead parrotfish (Bolbometopon muricatum), which can reach 4 feet (1.3 meters) long and 100 pounds (46 kg), the researchers were able to document the violent behavior with video and images.
The reef fish are named for their bulbous foreheads, which add to their eccentric, pouty lips and yellowish-to-pink faces.
“To us, it sounded like someone was firing a spear gun off close to our ears. Before we saw the behavior, we actually joked that the bumpbheads were head-butting like bighorn sheep,” study researcher Roldan MuÃ±oz, of the National Marine Fisheries Service, Beaufort Laboratory, in North Carolina, told LiveScience. “We were blown away when we actually witnessed the behavior.”