Thirteen years ago British scientists collected the largest hairy anglerfish ever seen, but it retains the title only due to its last meal. Roughly the size of a football, the creature’s distended stomach left researchers wondering for more than a decade what the deep sea fish’s final meal was. Very little is known about the hairy anglerfish’s diet and behavior, save that it lives at depths of over 3,000 feet below the surface of the ocean. The rarity of the specimen meant that researchers were reluctant to perform an autopsy on the fish, and it is only with the help of a CT scanner that scientist were able to peer into the anglerfish.
“The most important use of the CT scanner is to be able to look really intimately into the insides of animal but without doing any damage to it,” said James Maclaine, curator of fish at the United Kingdom’s Natural History Museum.
The CT scanner uses thousands of x-rays to create a detailed 3D image. With the help of modern technology, Maclaine was able to make out the creature sitting inside the anglerfish’s stomach. He speculated that the prey fish was drawn in by the lighted filament that anglerfish use to “reel in” prey, which gives the species its name. Maclaine consulted with fish bone experts to identify the angler’s last meal as a Reuleina attrite, a long and slender deep sea fish.
In addition to finally identifying the prey fish, Maclaine now had a detailed look inside one of the ocean’s rarest species—so rare that there are only 17 specimens in collections worldwide. This particular example was found during a research expedition in the Cape Verde Islands in 1999.
“We have only one specimen in our collection,” Maclaine said. “It’s the biggest one ever found.”
Hairy anglerfish are capable of puffing up their stomachs to consume large prey, a trait the fish developed to accommodate the relative lack of food in the ocean’s abyssal zone. The fish’s namesake hair is actually antennae used to detect passing prey, which the anglerfish then lures and ambushes.