Whales, along with dolphins and porpoises, are marine mammals classified within the scientific order Cetacea. Determining the exact count is complicated by the ongoing process of scientific discovery and taxonomic revision. Scientists use a detailed classification system to categorize this diverse group of animals. This system is primarily built upon the two ancient, distinct evolutionary paths these marine giants followed, leading to two major groupings. Understanding the types of whales requires looking at the total number of cetacean species found across the globe’s oceans and rivers.
The Fundamental Classification: Toothed Whales vs. Baleen Whales
All modern cetaceans are divided into two primary suborders: Odontocetes (toothed whales) and Mysticetes (baleen whales). These two groups diverged from a common ancestor approximately 34 million years ago, resulting in distinct physical and behavioral characteristics. The most obvious difference lies in their feeding apparatus. Odontocetes possess teeth for actively hunting prey, while Mysticetes have baleen plates for filter-feeding. Baleen is a fibrous material made of keratin that hangs in plates from the upper jaw, acting as a sieve to trap small organisms like krill and copepods. Toothed whales use their teeth to grasp fish, squid, and other marine mammals. Another key difference is their breathing anatomy: toothed whales have a single blowhole, while baleen whales possess a pair of blowholes.
The Current Global Census: How Many Species Exist
The current accepted count for all cetacean species—which includes all animals commonly called whales, dolphins, and porpoises—is approximately 90 to 94 species worldwide. The vast majority of these species belong to the toothed whale suborder, Odontoceti, which accounts for around 75 species. The baleen whale suborder, Mysticeti, is much less diverse in terms of species count, comprising only about 15 species. This significant difference in number is partially attributed to the more specialized feeding strategy of baleen whales, which limits the variety of habitats and prey they can exploit. The Odontocetes, with their more varied diet and hunting methods, have diversified into many more ecological niches.
Illustrating Diversity: Key Families and Representative Species
The 90-plus species of cetaceans are organized into numerous families that highlight the extraordinary range of size and behavior within the order.
Mysticete Families
Within the Mysticetes, the Rorquals (Family Balaenopteridae) are the most diverse group, including the largest animal on Earth, the blue whale, and the migratory humpback whale. Rorquals are characterized by their expandable throat grooves, which allow them to gulp immense volumes of water and food before filtering it through their baleen. Another important Mysticete family is the Right Whales (Family Balaenidae), known for their distinctive callosities on their heads.
Odontocete Families
The Odontocetes show even greater variety. The largest member is the sperm whale (Family Physeteridae), a massive, deep-diving predator. The Beaked Whales (Family Ziphiidae) are a mysterious group of deep-ocean dwellers, representing a large portion of the toothed whale species with over 20 accepted species. The most numerous family is the Oceanic Dolphins (Family Delphinidae), which contains about 38 species, including the killer whale (orca) and the pilot whales. Though many Delphinids are colloquially called dolphins, they are technically considered toothed whales and are included in the overall species count.
Why the Species Count Is Always Changing
The numerical count of whale species is not static because the scientific understanding of these animals is constantly evolving. Advances in technology, particularly genetic sequencing, frequently lead to taxonomic revisions where a single species is “split” into two or more distinct species based on DNA evidence. This is a common factor in the reclassification of cetaceans and directly increases the official species count. New species discoveries also occur, especially among the deep-diving and elusive beaked whales, which are difficult to study in their remote ocean habitats. For example, Rice’s whale was only recently recognized as a unique species, changing the total count of baleen whales. As researchers continue to explore the oceans, the current number of whale species will continue to fluctuate.