Whales possess mouth structures uniquely adapted for their aquatic existence. Unlike humans or other terrestrial animals, they do not have traditional lips. Their oral anatomy is shaped to efficiently capture food and navigate their underwater world, reflecting millions of years of evolution.
Whale Mouth Anatomy
Whales are categorized into two main types based on their feeding apparatus: baleen whales and toothed whales. Baleen whales (mysticetes) lack teeth. Instead, their upper jaws are lined with hundreds of stiff, fibrous baleen plates, made from keratin, the same protein found in human fingernails and hair. These plates vary in length and number by species, forming a fringed, comb-like structure for filtering.
Toothed whales (odontocetes) possess teeth, though their form and function vary greatly. These teeth are cone-shaped and used for grasping prey, not primarily for chewing. Tooth count ranges from a few, as in some beaked whales, to over a hundred in certain dolphins. Some, like the narwhal, feature a single elongated tusk, which is a specialized tooth.
Feeding Without Lips
The absence of traditional lips allows whales to employ specialized feeding strategies. Baleen whales are filter feeders, consuming vast quantities of small organisms like krill, copepods, and small fish by straining them from seawater. Their flexible jaws and expandable throat pleats allow them to engulf enormous water volumes, sometimes nearly doubling their weight in a single gulp. The water is then expelled through the baleen plates, trapping food to be swallowed whole. This efficient process allows some of Earth’s largest animals to sustain their massive bodies.
Baleen whales exhibit various feeding methods, including lunge feeding (rapidly swimming into dense prey with mouths open) or skim feeding (continuously filtering water while swimming). Gray whales bottom feed, sifting invertebrates from mud and water. An “oral plug” at the back of their mouths helps prevent choking by blocking the respiratory tract during massive gulps.
Toothed whales are predators that hunt individual prey. They use their diverse teeth to grip slippery fish, squid, or other marine mammals, often swallowing their catch whole. Many rely on echolocation, emitting high-frequency sounds and interpreting returning echoes to navigate and locate prey in dark or murky waters. Some species, like belugas, also use suction to pull prey into their mouths.
Evolutionary Adaptations
The distinct mouth anatomies of whales result from evolutionary adaptations to an aquatic lifestyle. Millions of years ago, whale ancestors transitioned from land, leading to significant changes in their skeletal and soft tissue structures. Baleen development in mysticetes was a major evolutionary shift, replacing teeth to exploit abundant, small prey through filter feeding. This adaptation allowed for immense body sizes, providing an energy-efficient way to consume large food quantities.
For toothed whales, jaw and tooth evolution was driven by effective prey capture and echolocation development. Their lower jaw plays a role in transmitting sound to the inner ear for this sensory ability. These oral structures, along with features like the dorsal blowhole for breathing and a streamlined body, show how whale anatomy is tuned for marine survival.