Whales populate every ocean, displaying a range of sizes from smaller dolphin species to the blue whale, the largest animal known to have ever existed. Their habitats are just as varied, spanning from warm equatorial waters to frigid polar regions. A key part of their adaptation to these environments involves their anatomy, but a common question arises about their teeth.
The Two Major Groups of Whales
A common misconception is that all whales possess teeth. In reality, cetaceans, the taxonomic order including all whales, dolphins, and porpoises, are divided into two suborders based on what is inside their mouths. The first group is the Odontoceti, or toothed whales.
The second suborder is the Mysticeti, commonly known as baleen whales. Instead of teeth, these whales have baleen plates in their upper jaws. This difference in oral anatomy is the primary feature used to classify all whale species and directly influences their feeding strategies.
Anatomy of Toothed Whales
The teeth of Odontoceti are homodont, meaning all the teeth are uniform in shape, appearing as simple cones. Each tooth consists of a core of dentin, covered by a layer of enamel on the crown and cementum on the root.
Unlike many mammals, toothed whales do not use their teeth for chewing. Their primary function is to grasp and immobilize prey before it is swallowed whole. The number of teeth varies dramatically between species, from the narwhal with its single tusk to some dolphin species that have over 250 teeth. This variation reflects the diverse diets found within this group.
Notable Examples of Toothed Whales
The sperm whale has a unique dental configuration. It has large, conical teeth located almost exclusively in its narrow lower jaw. The upper jaw contains sockets into which these lower teeth fit but lacks erupted, functional teeth of its own, an arrangement effective for hunting large squid.
Orcas, or killer whales, are apex predators with interlocking teeth, meaning the teeth of the upper and lower jaws fit together when the mouth is closed. This provides a strong grip for capturing and tearing a wide variety of prey, which can range from fish to marine mammals like seals and sea lions.
The narwhal is often called the “unicorn of the sea” due to the male’s tusk. This tusk is an elongated canine tooth that can grow up to 2.7 meters long. It grows in a spiral pattern from the left side of its upper jaw and is used to stun fish, but also functions as a sensory organ to detect changes in water pressure and salinity.
The Alternative to Teeth
For Mysticeti, the alternative to teeth is baleen, which enables filter-feeding. Baleen is composed of keratin, the same protein in human hair and fingernails. It consists of long, flexible plates that hang from the whale’s upper jaw in a comb-like fashion. These plates are frayed on the inner edge, creating a dense mat of bristles.
A baleen whale feeds by taking in an immense volume of water containing small prey like krill and small fish. The whale then closes its mouth and uses its large tongue to press water out through the sides, trapping food against the baleen bristles. The filtered prey is then scraped off the baleen and swallowed.