Whales are marine mammals that inhabit oceans across the globe. Understanding the different “types” of whales involves looking at how scientists classify these diverse creatures. This classification encompasses major biological groups, families, and individual species, each adapted to their marine environments.
The Two Major Groups of Whales
All whales belong to the order Cetacea, which is fundamentally divided into two distinct suborders: baleen whales (Mysticeti) and toothed whales (Odontoceti). These two groups represent a primary evolutionary split that occurred approximately 34 million years ago. The most significant difference lies in their feeding apparatus. Baleen whales possess specialized keratin plates for filter feeding, while toothed whales have teeth designed for catching prey. This fundamental distinction dictates their diets, hunting strategies, and many aspects of their anatomy and behavior.
Baleen Whales
Baleen whales are characterized by their unique filter-feeding mechanism, utilizing baleen plates that hang from their upper jaws to sieve small organisms from the water. These whales consume vast quantities of tiny prey, such as krill, small fish, and copepods. Different species employ various feeding strategies, including “lunge-feeding” where they engulf large volumes of water and prey, or “skim-feeding” where they swim with open mouths through dense patches of food.
The blue whale (Balaenoptera musculus), the largest animal known to have ever existed, can reach lengths of 30 meters and weigh up to 190 metric tons. Humpback whales (Megaptera novaeangliae) are recognized by their exceptionally long pectoral fins and acrobatic breaching behaviors. Gray whales (Eschrichtius robustus) are unique bottom-feeders, sifting through seafloor sediments to find crustaceans and other invertebrates.
Toothed Whales
Toothed whales are predatory marine mammals that possess teeth, which they use to capture and hold onto their prey. This group includes larger whales like the sperm whale, as well as all dolphins and porpoises. Toothed whales often use echolocation, emitting sound waves and interpreting the echoes to navigate and locate prey in their underwater environment.
The sperm whale (Physeter macrocephalus) is the largest toothed whale, known for its massive head and deep-diving abilities to hunt squid. Orcas (Orcinus orca), often called killer whales, are apex predators within this group, recognized for their distinctive black and white coloration and complex social structures. Dolphins, like the bottlenose dolphin (Tursiopsis truncatus), are highly intelligent and social, often displaying cooperative hunting behaviors. Porpoises, generally smaller than dolphins with spade-shaped teeth and triangular dorsal fins, are also included.
Understanding the Total Count and Ongoing Discoveries
The approximate total number of recognized whale species, encompassing both baleen and toothed whales (including dolphins and porpoises), is currently around 90. Specifically, there are about 15 to 16 species of baleen whales and roughly 73 to 75 species of toothed whales. This number can fluctuate slightly between different sources or over time, as the classification of whale species is a dynamic field subject to ongoing scientific research.
New species are occasionally discovered, and existing species can be reclassified based on new genetic or anatomical evidence. For example, Janjucetus dullardi, a new ancient whale species, was recently identified from a 25-million-year-old fossil, providing insights into early whale evolution. Similarly, some killer whale populations, once considered a single species, are now recognized as distinct species based on detailed scientific analysis.