Beluga whales are often recognized by their striking white coloration and distinctive rounded heads. These marine mammals frequently spark curiosity about their classification, leading many to wonder if they are whales or dolphins. The question arises due to their size and some shared characteristics with both groups of marine animals.
Belugas: The Scientific Classification
Beluga whales (Delphinapterus leucas) are indeed whales. They belong to the suborder Odontoceti, which encompasses all toothed whales.
This suborder includes a diverse range of marine mammals, such as sperm whales and beaked whales, alongside dolphins and porpoises. While dolphins are also part of the Odontoceti suborder, they belong to a different family, Delphinidae. Belugas, on the other hand, are classified under the family Monodontidae. The only other living member of this family is the narwhal, another Arctic species.
Distinguishing Whales from Dolphins
The broader category of cetaceans, which includes all whales, dolphins, and porpoises, is divided into two main suborders: Mysticeti and Odontoceti. Mysticeti are baleen whales, characterized by filter-feeding plates instead of teeth, and typically have two blowholes. These include the largest whale species, such as blue whales and humpbacks. Odontoceti, or toothed whales, possess teeth and generally have a single blowhole.
The term “whale” can refer to any large cetacean, or specifically to baleen whales, while dolphins are generally smaller, more agile members of the toothed whale group. Within the toothed whale suborder, significant size variations exist; for instance, the sperm whale is much larger than most dolphins. Dolphins often have a prominent beak and a curved dorsal fin, whereas many larger toothed whales, like belugas, lack a dorsal fin. Dolphins often exhibit social behaviors in large pods and are playful.
Unique Characteristics of Beluga Whales
Beluga whales possess distinct features. Adults are known for their striking all-white coloration, which helps them camouflage in their icy Arctic and sub-Arctic habitats. Calves are born dark gray or brown and gradually lighten to white as they mature, a process that can take several years. Unlike most other cetaceans, belugas have unfused cervical vertebrae in their necks, allowing them to turn their heads from side to side and nod, similar to humans. This flexibility aids them in navigating complex underwater environments and hunting prey.
A prominent, rounded protuberance on their forehead, known as a melon, is a defining characteristic. This melon is composed of fatty tissue and is highly flexible, allowing belugas to change its shape. The melon plays a role in echolocation, focusing and modulating the sounds they produce to navigate and locate objects in their environment. Recent studies suggest that belugas can also intentionally alter the shape of their melon as a form of visual communication during social interactions.
Belugas are renowned for their wide range of vocalizations, earning them the nickname “canaries of the sea.” They produce an array of sounds, including whistles, clicks, chirps, and squeals, which are used for communication within their social groups and for echolocation. These sounds are generated by moving air between nasal sacs near their single blowhole, as they lack vocal cords.
Belugas are opportunistic feeders, with their diet varying based on location and season, commonly including fish like Arctic cod, salmon, and herring, as well as crustaceans and mollusks. They are adapted to life in cold waters with a thick layer of blubber, which can account for up to 40% of their body weight, providing insulation and energy reserves. The absence of a dorsal fin also helps them navigate and swim easily under ice.