Crustaceans

It begins with a dead whale on a Boston shoreline...not an unusual occurrence. But the things that claw their way out of the blubber are unusual. A cast of giant crabs, evolved over centuries, make their way to the city using the sewer system. Soon they are swarming around Manhattan, hunted by a SWAT team tasked with ridding the city of the menace...before the menace rids itself of the city.