Baleen

Baleens, also called "baleen plates", are special triangular sheets of keratin found inside the mouth of baleen whales. These sheets form a filter-feeding system that helps the whale catch food. When a whale opens its mouth to take in water, it pushes the water out through the baleen plates, keeping tiny creatures as food.

A baleen is similar to a bristle and is made of keratin, the same substance found in human fingernails, skin, and hair. Depending on the species, baleen plates can be from 0.5 to 3.5 metres long and weigh up to 90 kilograms. They have hairy edges called baleen hair or whalebone hair.

Historically, people used baleen for many purposes and called it whalebone, although this name is not correct. The baleen plates are broader at the base and have been compared to sieves or Venetian blinds. Some whales, like the bowhead whale, have baleen of different lengths, while others, like the gray whale, use only one side of their baleen.

Etymology

The word "baleen" comes from a Latin word, bālaena, which is related to a Greek word phalaina. Both of these words mean "whale".

Evolution

Scientists think baleen, the special filter in the mouths of baleen whales, started forming a long time ago—about 30 million years back. We only have fossils that are 15 million years old because baleen doesn’t usually turn into fossils. But we can see changes in old whale skulls that show baleen was around earlier than the fossils say.

Experts believe baleen may have started from a hard, gummy upper jaw, similar to what Dall’s porpoises have today. Over time, whales changed from having teeth to using baleen to catch food. Young whales today still grow teeth before they develop baleen, but they lose the teeth as they grow up. This change happened step by step, allowing whales to use filter feeding while still keeping some of their old ways of catching food.

Filter feeding

A baleen whale uses special plates in its mouth to feed. When it wants to eat, the whale opens its mouth wide to take in water filled with tiny food like krill, copepods, small fish, and sometimes even birds. The whale then pushes the water out through these plates, which act like a sieve, leaving the food behind for the whale to eat.

Mechanical properties

Whale baleen is a strong and flexible material made mostly of a special protein called keratin. It is found in the mouths of whales and is used for many things because of its strength and flexibility.

Baleen has a special structure with tiny tubes inside. These tubes have more calcium than the outer parts, which helps make baleen strong. When water is added, baleen changes how it reacts to pressure, making it even more useful. Cracks in baleen also behave differently depending on their direction, helping the material resist breaking.

Human uses

People once used baleen, often called "whalebone," to make many flexible and strong items like baskets, backscratchers, collar stiffeners, buggy whips, parasol ribs, switches, crinoline petticoats, farthingales, busks, and corset stays. It was also used to crease paper without damaging it and sometimes in cable-backed bows. Today, people mostly use materials like plastic and fiberglass instead. In the United States, a law from 1972, the Marine Mammal Protection Act, makes it illegal to trade or move products made from marine mammals.