Whales can be divided into two types by the way they feed – baleen whales (Mysticetes) and toothed whales (Odontocetes).
Baleen whales are ‘batch feeders’ – they use their plates of baleen to filter huge numbers of tiny prey out of the water.
Toothed whales hunt their prey one by one. They use echolocation to find it and usually swallow it whole.
Baleen whales – Gulpers, skimmers, and silt sifters
Baleen whales can be divided into three groups according to how they filter their food.
The rorquals, such as humpback whales are gulpers. They take in huge amounts of water with their prey, their pleated throats billowing out to accommodate it. They then force the water out, straining the food through the mesh of baleen.
Right whales skim-feed. They cruise through the water with their enormous, arched mouths open, continuously filtering out prey.
Gray whales are silt sifters. They pump water and sediment from the seafloor through one side of their mouths, across their baleen, and out the other.
Baleen – a fantastic filter
How does baleen work? Plates of it hang from the upper jaw of baleen whales. The inside edge of each plate has a hairy fringe. These fringes knit together to form a fibrous mat for straining prey from the water.
Coarseness or fineness of baleen reveals what a whale feeds on. The fine baleen on display in the exhibition comes from a right whale, which feeds on zooplankton – near-microscopic animals. Gray whales have the coarsest baleen, as they filter sediment from the seafloor for crustaceans.
In the past, baleen has been called ‘whalebone’, even though it’s made of keratin, the same stuff your fingernails are made of. Manufacturers used whalebone to make various products requiring flexibility. Plastics replaced baleen in the 20th century.
Toothed whales either grab prey with their teeth or suck them directly into their mouths. These whales tend to eat individual animals, such as squid, fish, and, in some cases, other marine mammals.
Killer whales, porpoises, and most dolphins grip prey between their jaws. They then work the meal into their mouth and swallow it. These social animals often hunt together.
Sperm whales have an impressive set of teeth, but they don’t use them for feeding. They use suction, as do beaked whales and some dolphins. The whale zooms in on its prey until it’s close enough to suck the meal into its open mouth.