Blue whales do not possess teeth like most other mammals. Instead, these immense marine creatures belong to a specialized group of whales known as baleen whales (Mysticeti). This unique adaptation allows them to consume vast quantities of tiny organisms, which form the basis of their diet.
Baleen: The Blue Whale’s Unique Filter
Baleen is a filtration system located inside the mouths of baleen whales, hanging from their upper jaw. These plates are composed of keratin, the same protein that forms human hair and fingernails. Each baleen plate has a rigid structure at the gumline, and its inner edge features a fine, bristly fringe. Approximately 350 baleen plates grow parallel to each other and perpendicular to the jaw, resembling the slats of a vertical window blind. These plates can reach lengths of up to three feet in blue whales, and their bristly fringes interlock to form a dense, sieve-like mat designed to efficiently trap small prey from the water.
Filter Feeding Explained
Blue whales employ a feeding strategy known as “lunge feeding.” The whale accelerates to engulf enormous volumes of water and prey, primarily krill. Their throat pleats, which are grooves running along their underside, expand significantly, allowing their mouth and throat to balloon outwards and hold a volume of water that can exceed their own body mass.
Once the water and krill are taken in, the whale contracts its throat muscles and uses its large tongue to push the water back out through the baleen plates. The baleen acts as an effective sieve, trapping the tiny krill inside while allowing the water to be expelled. An oral plug shifts to protect the whale’s respiratory and digestive tracts, preventing choking. This method allows blue whales to consume approximately 4 tons of krill daily to sustain their massive size.
Whale Classifications: Toothed vs. Baleen
Whales are broadly categorized into two suborders: Mysticeti (baleen whales) and Odontoceti (toothed whales). Blue whales, along with humpback and right whales, are examples of baleen whales. This group is characterized by their immense size, with the blue whale being the largest animal on Earth.
Toothed whales, in contrast, possess teeth and include species such as dolphins, porpoises, orcas (killer whales), and sperm whales. Their feeding strategies differ from baleen whales; toothed whales hunt and consume larger prey like fish, squid, and other marine mammals. Many toothed whales also employ echolocation to locate their prey.