Amazingly, this whale is known to live to over 100 years of age, a fact established by the discovery of stone harpoon heads (out of use since the late 1800s) in the flesh of specimens. The diet consists of planktonic crustaceans, which are filtered through the baleen plates (7). Bowhead whales often skim-feed on the surface of the sea but also gather food from the sea floor. To insulate against the cold Arctic waters, bowhead blubber may be 70 centimetres thick and the whales can break through ice of a foot deep to make breathing holes (3). Bowheads are slow breeders and maturity may not be reached for 20 years. A single calf is born every three or four years after a gestation period of about 13 months (3).