baleen - Evolution of baleen, Baleen in filter feeding, Uses of baleen

A fibrous material from the mouth of some species of whale; forms a sieve during feeding; formerly used in manufacturing, when strong, light, flexible material was needed (eg to strengthen women's corsets); also known as whalebone (though it is not in fact bone).

Baleen makes up baleen plates, which are arranged in two parallel rows that look like combs of thick hair; they are attached to the upper jaws of baleen whales. Whales are the only vertebrate group to use this method of feeding in great abundance (flamingos and crabeater seals use similar methods, but do not have baleen), and it has allowed them to grow to immense sizes. The Blue Whale, the largest animal ever to live, is a baleen whale.

Depending on the species of whale, a baleen plate can be 0.5 to 3.5 m (2 to 12 ft) long, and weigh up to 90 kg (200 lb).

The word "Baleen" derives from Early Modern English word meaning "whale".

Evolution of baleen

The oldest true fossils of baleen are only 15 million years old, but baleen rarely fossilizes, and scientists believe it originated considerably earlier than that. Currently, baleen is believed to have evolved around thirty million years ago, possibly from a creature with a hard, gummy upper jaw, similar to that found on Dall's porpoise today, which are, at a microscopic level, almost identical to baleen.

Curiously, many early baleen whales also had teeth, but these were likely used only peripherally, or perhaps not at all (again, similar to Dall's porpoise, which catches squid and fish by gripping them against its hard upper jaw).

Baleen in filter feeding

A whale's baleen plates play the most important role in its filter feeding process. In order to feed, a baleen whale opens its mouth widely and scoops in large volumes of water, which inevitably contains large quantities of the plankton it feeds on.

Uses of baleen

Baleen plates were formerly used in buggy whips and parasol ribs, and to stiffen parts of women's stays and dresses, like corsets. It was also formerly believed that baleen plates could be obtained from whale fins.