Baleen Whales

Posted by John Blatchford Mar 6, 2008

Whalebone

The Baleen Whales do not have teeth; instead they have fringed plates made of keratin (the material that makes hair and finger nails). These ‘baleen plates’, also known as ‘whalebone’, are used to sieve small animals from the water. Right Whales and Bowheads feed by swimming along with the mouth open and straining out small animal plankton, Gray Whales scoop up sediment from the ocean floor and feed on the small crustaceans that live in the mud and sand, and Pygmy Right Whales probably feed on copepods – although very little is known about them.

Rorquals

All other Baleen Whales have pleats in the throat to allow the mouth to expand, and they are known collectively as the ‘rorquals’. They do not so much skim the water as gulp it, with the ‘pleats’ stretching to form an enormous mouth which can hold up to 100 tons of food and water in the case of the Blue Whale. Blue Whales, Fin Whales, Sei Whales and the small Minke Whales all eat plankton, but Bryde’s Whale, the Pygmy Bryde’s Whale and the Humpback prefer fish. That is all of the rorquals except for Balaenoptera omurai which was only recently discovered and has no common name as yet.

Classification

The possession of whalebone is common to all of the suborderMysticeti, but their exact relationships to each other are not clear. They all evolved from toothed ancestors and were probably all fish-eaters in the past. The change of diet (of most of them) has put them very close to the start of the ocean food-chain, allowing them to harvest the enormous numbers of small planktonic organisms which feed directly on the microscopic phytoplankton. This abundant and nutritious diet has allowed some of them to become the largest animals on earth.