What Is a Toothless Whale and How Do They Eat?

The vast oceans are home to the largest animals on Earth, yet many of these giants operate without a single tooth. These creatures belong to a group of whales known as Mysticeti. The absence of teeth raises the question of how they consume the immense amount of food required to sustain their bodies. They have developed a unique method for feeding that sets them apart from other marine animals.

The Baleen Feeding System

Instead of teeth, Mysticeti possess a specialized structure called baleen. This consists of hundreds of overlapping plates that hang from the whale’s upper jaw. Each plate is made of keratin, the same protein in human hair and fingernails, and features coarse, hair-like bristles on its inner edge that form a dense mat. This structure functions as a filtration system to capture large quantities of small prey.

The feeding process involves the whale engulfing a massive volume of water, which can sometimes equal its own body weight. The whale’s throat has long grooves, or pleats, that extend from its chin to its navel, allowing the throat to expand dramatically. Once its mouth is full, the whale uses its large tongue to press upwards against the palate, forcing the water out.

As the water is expelled, the baleen plates act like a sieve. The interlocking bristles trap the small prey inside the whale’s mouth, separating it from the water. The whale then swallows the collected food. This method allows them to subsist on a diet of tiny organisms like krill, copepods, and small schooling fish.

Common Toothless Whale Species

Among the most well-known baleen whales is the blue whale, the largest animal ever to have lived. Blue whales are “lunge-feeders,” a technique that involves accelerating to high speed and then opening their mouths to engulf huge volumes of water and krill. This method is energetically costly, but the payoff in captured prey is enough to fuel their immense bodies.

Humpback whales exhibit a more complex feeding strategy. They are known for “bubble-net feeding,” a cooperative behavior where a group of whales swims in a shrinking circle while blowing bubbles below a school of fish. The rising bubbles create a “net” that corrals the prey, allowing the whales to surface in the center with their mouths open, consuming thousands of fish.

Right whales employ a technique known as “skim-feeding.” They swim slowly near the surface with their mouths open, continuously filtering plankton and small invertebrates from the water. Their fine baleen bristles are well-suited for capturing the copepods that make up a large part of their diet. This method allows them to feed for extended periods without the high energy expenditure of lunge-feeding.

Key Differences from Toothed Whales

The fundamental distinction between Mysticeti and toothed whales (Odontoceti) is the presence of baleen instead of teeth. This anatomical difference dictates their feeding ecology. While baleen whales are filter-feeders, toothed whales are active hunters that pursue individual prey such as fish, squid, and sometimes marine mammals.

Another distinguishing feature is the number of blowholes. Baleen whales possess two blowholes on top of their head, which often produce a V-shaped spout. In contrast, toothed whales have a single blowhole.

Baleen whales are also significantly larger than toothed whales. This group includes all giant whale species, a characteristic linked to the efficiency of filter-feeding. The ability to strain vast amounts of tiny prey from the water has allowed these animals to evolve to sizes unmatched by any predator that hunts single prey.