University of Delaware gate

A marine biologist weighs in on last week's shark attack that killed a woman off the coast of Maine.

Most of the time, sharks bite things to see exactly what they are, said UD's Aaron Carlisle.

"Sharks don't have hands, they're very curious, the only way they can figure out what something is, if it's edible, they take bites of it, and actually, they're very delicate--I mean, if the shark, if you ever could see a natural predatory event--when they actually bite and mean it, it's very different than what most people experience," said Carlisle.

63-year-old Julie Holowach was killed by a great white shark off Maine's Bailey Island, and Carlisle traced an increase in shark sightings in the New England area to the recovery of the population of grey seals, a favorite prey item for sharks.