for National Geographic News
Usually it's only jellyfish and skin-pinching crabs that swimmers worry about along the beaches of southwest England. But this summer they have something else on their mindsthe ocean's awesome predator, the great white shark.
The perceived threat, however slim, follows reports of a large, unidentified shark feeding 20 yards (18 meters) off the west coast of Devon.
Experts disagree on whether it was a great white, which can easily be confused with another species of shark commonly found in these waters.
However, the publicity given to the sighting has raised a number of interesting questions. Why, for example, do great white sharks not ordinarily venture into this part of the ocean?
And if it was a great white spotted off Devon, could this be the first of many following their traditional food source? For some years now, many species that are also the great white shark's prey have been observed migrating farther northpossibly because the sea around the U.K. is getting warmer. Is it not inevitable that the great whites will follow in their wake?
The shark thought to be a great white was recently spotted by Chaynee Hodgetts while on vacation.
The teenager, who wants to become a marine biologist, watched the shark from cliffs for ten minutes as it attacked a shoal of fish. Using binoculars, she judged its length at 12 feet (3.66 meters) by comparing it with common dolphins chasing the same shoal.
Having seen detailed notes taken by the 15-year-old, experts say her description closely matches that of a great white (Carcharodon carcharias)a species never before recorded in U.K. waters.
She reported her sighting to Rolf Williams, a shark expert at the National Marine Aquarium in Plymouth, England.
"It's tantalizing and we're taking it seriously," he said: "We scrutinized Chaynee very thoroughly to get the best information we could. We'll never know for certain, but some of her observations strongly suggest a great white."
Williams says there are just two other sharks found off southwest England that could be mistaken for this super-predator.
The basking shark, which can grow to 36 feet (11 meters) in length, is certainly big enough, but Williams rules it out as the species is a plankton-eater that wouldn't attack shoals of fish.
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