Fearless cookiecutter shark taking on great whites, UF scientists find
Published: Monday, February 4, 2013 at 12:58 p.m.
Last Modified: Monday, February 4, 2013 at 12:58 p.m.
Small but mighty: What's true on land might also be true in the ocean.
Recently, scientists unveiled the first photographic evidence that a cigar-shaped shark less than 2 feet long — known as the cookiecutter shark — bit one of the oceanic giants 10 times its size — the great white shark.
Yannis Papastamatiou, a marine biologist in the division of ichthyology at the Florida Museum of Natural History in Gainesville, was one of the authors of a study published in the January issue of the journal Pacific Science, which describes the cookiecutter shark's bite wound near the mouth of a great white found in the waters off Guadalupe Island in the Pacific.
The cookiecutter shark, named for its characteristic bite that is unique among sharks, scoops out a neatly round piece of flesh from its prey.
"They have a fairly distinct skull and musculature and are really evolved to scoop these circular bites out of animals," Papastamatiou said. "There is no other shark with a similar adaptation."
The sharks also have tiny upper teeth and lower teeth that "look like a picket fence with razor sharp edges," said Christopher Lowe, a professor at California State University and another author of the study. This allows their upper teeth to sink in as their lower teeth dig and twist out their victim's flesh.
But then, they are done.
"Their strategy is not a kill — they are just getting one bite," Papastamatiou said. They do feast on a number of species, though, and have left bites on dolphins, whales and tuna. They ingest squid and small fish whole.
In 2009, a man doing an inter-island nighttime swim in Hawaii got bit, and people drowned at sea have been found with bites.
The sharks also have taken chunks out of submarines and oceanographic equipment.
"Think of it like a buffet table for a cookiecutter. They take bites out of everything," Lowe said, adding that the documented bites have increased, he suspects, because the sharks' increased access to feeding has allowed them to reproduce faster.
But the cookiecutters are still an elusive breed, and fairly hard for scientists to study because they generally hang out in the deepest part of the ocean (over half a mile down) and come to shallower waters only at night, which is likely their most active feeding time.
As Papastamatiou explained, cells in their belly produce light to match moonlight, which makes them disappear in a predator's eye. However, they have a dark band behind their head that a predator mistakes for a ring of tiny fish. And that might be how a cookiecutter deceptively lures bigger sharks and other animals toward it, then shocks them with its own bite before sneaking away, Papastamatiou said.
"The cookiecutter moves around pretty fast. We don't know how (the other shark) responded. It was more than likely a startled response. It's got to be fairly shocking."
But the wounds do heal, and so far, they haven't been known to cause long-term damage to victims, although Papastamatiou said there might be an immune system consequence, particularly in animals such as swordfish, which can be covered with bites if they are not entirely eaten.
And cookiecutter bites on fish caught and sold at a market do detract from the fish's value, Papastamatiou added.
"They actually do have some economic impact. At fish auctions, the market value of the fish goes down with cookiecutter bites."
The challenge for scientists now is to study the cookiecutters while they are in attack mode, since they mostly have been caught accidentally in fishing nets.
"My dream is to detect them and track them in the wild," Papastamatiou said. "We've developed a lot of theories about how they behave, but to be able to find them is really the hard part."
Contact Kristine Crane at 338-3119 or firstname.lastname@example.org.
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