Blue Whale

The blue whale is the largest animal known to have existed. Adult males average about 25 m and females about 27 m, while the longest confirmed specimen measured 33.5 m. Its body is slate to grayish-blue with lighter mottling, especially across the back and shoulders. Microorganisms may give the underside a yellowish cast. The whale has a broad upper jaw, blunt rostrum, a small dorsal fin, and 50–90 expandable throat grooves extending from the chin beyond the navel. (Animal Diversity Web)

Blue whales inhabit open oceans worldwide, ranging from tropical seas to polar drift ice. Most populations migrate, spending winters in lower latitudes before moving toward productive high-latitude feeding waters during spring and summer. Individuals or groups of two or three are most common, although larger feeding aggregations occur. Their diet consists principally of krill captured by filter feeding, with other plankton and small fish sometimes included. An adult may consume three to four metric tons of krill in a single day. (Animal Diversity Web)