The largest recorded fin whale was a female about 27 m long, weighing more than 100 tons. Fin whales are sleek, fast swimmers. Some make long distance migrations, spending summers in cold, high latitude northern or southern oceans and returning to warmer waters in winter. Some individuals have been returning to the Gulf of Maine for up to 20 years, but their wintering grounds have not all been located, and they are not usually seen in groups near islands or coasts, making them hard to study. Like other rorquals, fin whales have accordion-like pleats that let them expand the throat and mouth while filling it with water and prey, which is likely to be krill and small schooling fish. But unlike the others, they lunge-feed instead of skimming, by accelerating quickly and turning or rolling into a vast school of prey. Then they contract the throat folds, forcing the water out through the fringed baleen plates and leaving food in the mouth. One of the unexplained oddities of the fin whale is color asymmetry: the lower jaw is white on the right side, black on the left. Some believe this is somehow a feeding adaptation.

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Mammal Species of the World
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