Watch: Australian Fishermen Haul in Swordfish Covered in Strange Round Holes

An Australian fishing boat made a rare find recently when it caught a swordfish with a bunch of holes gouged in its flesh. The odd wounds are the hallmark of a small attacker with a ferocious bite: the cookie cutter shark. Though its name sounds sweet, cookie cutters are no treat for any large predator unlucky enough to encounter them. The foot-and-a-half long shark latches onto prey with suction lips, digs in with its razor-sharp teeth, and spins its body to gouge out a plug of flesh.

The unusually vicious attack was discovered by Captain T.K. Walter and his crew while fishing for tuna and swordfish in the Coral Sea.

“For those that don’t know, a cookie cutter shark is just a small shark with obviously a very fearsome set of triangle shaped teeth,” Walter says in a video that shows the swordfish being hauled onto the deck with holes of varying sizes visible in its body. “What they do is they just come racing along and race up, grab a hunk of meat, and race off again. Grab a hunk, twist, and take off.”

Because a cookie cutter bite is not fatal, the sharks are technically considered parasites rather than predators. But the unusual number of wounds suffered by the swordfish—more than a dozen oval holes gouged from cheek to tail on one side alone—prompted the captain to theorize that the unlucky pelagic was the victim of a pack attack. “Man, he’s been savaged,” Walter can be heard to say on the video. “I have never seen an attack like that before in 40 years of doing this,” He later told Newsweek. “They made more than a snack out of him that’s for sure.” 

Cookie cutters spend their days in depths up to 3,000 feet, then move up through the water column at night to hunt. Their undersides contain light-emitting cells that create a vivid green glow, which is thought to blend in with natural light streaming down from above (rendering them invisible to predators below) while attracting larger fish around them to investigate.

A dark ring around the cookie cutter’s neck that resembles the silhouette of a fish aids in the deception. The small shark then latches on with its upper teeth and uses its unique bottom teeth—which is actually a single fused tooth resembling a saw-like blade—to scoop out flesh. Like other sharks, cookie cutters lose and replace their teeth regularly. However, they’re the only member of the shark family to shed all their teeth at once—and they’re thought to swallow their chompers as a way of recycling calcium.  

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The ferocious little sharks target medium and large-sized fish as well as mammals like dolphins, seals, sea lions, and whales. Even great whites have been observed with the tell-tale round wounds of a cookie cutter bite, and the pugnacious hunters have been known to disable nuclear submarines.