animals

Shark scoops out flesh like melon baller

U. FLORIDA (US) — Don’t let their size fool you. At only two feet, cookiecutter sharks can do serious damage by scooping out flesh with their unique jaws, leaving crater-like wounds.

Unlike other sharks, a cookiecutter’s teeth are connected at the bottom in the lower jaw. When feeding, the shark bites its victim and then rotates to remove a plug of flesh, “kind of like using a melon baller,” says George Burgess, director of the International Shark Attack File at the University of Florida.

New research published in the journal Pacific Science details the first attack on a live human by a cookiecutter. The sharks often feed at night near the surface of open ocean tropical waters

“Not only is it painful, but it presents a difficult circumstance for recovery in the sense that there has to be plastic surgery to close the wound and you have permanent tissue loss,” Burgess says. “It’s not as scary as Jaws, but it’s very different from any other kind of attack we have in the International Shark Attack File because of the size of the shark and the modus operandi.”

During the March 16, 2009, incident the shark repeatedly attacked a long-distance swimmer attempting to cross the Alenuihaha Channel from Hawaii to Maui. After sunset, the victim said the first bite on his chest felt “like a pin prick.” He then was bitten on the left calf while climbing into the rescue kayak following him during the swim.

The International Shark Attack File lists two other incidents involving cookiecutters, both judged to be inflicted post-mortem. Cookiecutters inhabit deep tropical waters and their bites have been found on a variety of deep-sea animals, including tuna, whales, dolphins, and swordfish.

“They have the biggest teeth of any shark in relation to the size of their jaws,” Burgess says. “They look like the cartoon sharks you see with oversized teeth.”

The victim reported seeing squid before the attack. Like squid, cookiecutters are bioluminescent, producing their own light on parts of their bodies and most probably use this specialization to hide among squid while larger fish, such as tuna, prey on the squid.

The sharks then surprise the larger fish, taking bites before quickly leaving the scene.

A type of dogfish shark, cookiecutters do not kill their fish victims and the wounds they inflict may be useful as biological markers. Because they are known to only dwell in tropical waters, scientists can use the bites to better understand the movement patterns of their victims.

“When we see a killer whale in Alaska with the mark, it tells us the whale traveled there from the tropics,” Burgess says. “We can also judge how long ago it happened by how much the wound has healed.”

Attempts to collect a live specimen over the past few years are “turning out to be more difficult than our white shark program,” says John O’Sullivan, curator of field operations and a senior collector at the Monterey Bay Aquarium in California.

“We have to be careful because of how different species occupy a niche—how that varies is not at all understood,” O’Sullivan says.

Cookiecutter sharks bite their victims, like this tuna, then rotate to remove the flesh. (Credit: John Soward)

“These animals are very small and very aggressive in behavior. People say, ‘Thank God these things don’t get big.’ ”

The study was led by Randy Honebrink of the Hawaii Division of Aquatic Resources.
More news from University of Florida: http://news.ufl.edu/

Related Articles