Whales are not a uniform group, and not all of them have teeth. The order Cetacea, which includes all whales, dolphins, and porpoises, is divided into two distinct suborders based on their feeding anatomy. These are Odontoceti, the toothed whales, and Mysticeti, the baleen whales. This difference in mouth structure represents a major evolutionary split, leading to two separate feeding strategies and body plans. The presence or absence of teeth determines the whale’s diet, social structure, and hunting behavior.
The Toothed Whales and Their Specialized Teeth
The teeth of Odontocetes are highly specialized and function differently from those of land mammals. Most toothed whales, such as orcas, dolphins, and sperm whales, possess teeth that are uniform in shape, a characteristic known as homodonty.
These teeth are simple cones designed for grasping and holding prey, rather than for chewing or grinding. A toothed whale generally swallows its food whole or in large chunks, using its teeth only to secure prey like fish or squid. The number of teeth varies dramatically, ranging from a few vestigial teeth in some beaked whales to more than 240 in the La Plata river dolphin.
Specialized teeth are seen in species like the narwhal, where the male’s most prominent feature is a single, elongated tooth that forms a tusk up to 10 feet long. This tusk is thought to be a sensory organ used to explore the environment and aid in feeding. The sperm whale, the largest toothed whale, has between 36 and 50 large conical teeth only on its lower jaw, which fit into sockets in the upper jaw.
The Baleen Alternative
Whales in the suborder Mysticeti, which includes the largest species like the Blue Whale and Humpback Whale, do not develop functional teeth. Instead, they possess an elaborate filtration system made of plates called baleen. These structures are composed of keratin, the same fibrous protein found in human fingernails, hair, and animal horns.
The baleen plates hang in two rows from the upper jaw, functioning like a sieve to capture small organisms from the water. Depending on the species, a baleen whale can have between 150 and 400 plates on each side of its mouth. The inner edge of each plate is frayed into fine, hair-like bristles that create a dense mat inside the mouth.
When a baleen whale feeds, it takes in water and prey, then uses its tongue to push the water back out through the baleen. The fine bristles trap the small prey, such as krill, copepods, and tiny fish, while the water passes freely back into the ocean. This mechanism allows these massive animals to sustain themselves on some of the smallest marine organisms.
How Structure Dictates Diet and Hunting
The difference between teeth and baleen is the primary factor determining a whale’s ecological role and hunting behavior. Toothed whales are active, predatory hunters that pursue individual, larger prey items. Their conical teeth are suited for grabbing and securing fast-moving animals like fish, squid, and even other marine mammals, such as the Orca.
Many toothed whales, including dolphins and porpoises, utilize echolocation, emitting sound pulses to locate and target their prey. Their feeding involves a high degree of precision and often cooperative hunting within social groups called pods.
In contrast, baleen whales are filter feeders that consume large volumes of small, aggregated prey. Their hunting methods are categorized into distinct strategies that maximize the efficiency of their baleen plates. Skim feeders, such as Right Whales, swim slowly with their mouths open through dense patches of plankton, continuously straining organisms from the water. Lunge feeders, including Blue Whales and Humpback Whales, employ a gulping technique, accelerating to engulf huge mouthfuls of water and prey before expelling the water through their baleen. Gray Whales utilize a unique bottom-feeding method, rolling onto their side to scoop up sediment and water from the seabed, filtering out small crustaceans.