Many people wonder if orcas, commonly known as killer whales, are actually whales or if they belong to a different group of marine mammals. This confusion often arises from their imposing size and the popular name “killer whale,” which suggests a direct relation to larger whale species.
Orcas Are Dolphins
Orcas, scientifically named Orcinus orca, are the largest members of the oceanic dolphin family, Delphinidae. Despite their common name, they are not baleen whales, like humpbacks or blue whales. Dolphins are toothed whales, characterized by streamlined bodies, prominent dorsal fins, and conical teeth. Orcas share these characteristics, classifying them within the dolphin family. They possess a single blowhole, typical for toothed whales, and use echolocation for navigation and hunting.
Understanding Their Family Tree
All whales, dolphins, and porpoises belong to the order Cetacea. Within this order, there are two main suborders: Mysticeti (baleen whales, which filter feed) and Odontoceti (toothed whales). Orcas fall under Odontoceti, classifying them as toothed whales. The family Delphinidae, also known as oceanic dolphins, is the largest family within the toothed whales, containing 37 species. Orcas are part of this family.
The name “killer whale” is a misnomer that dates back to ancient sailors who observed orcas hunting larger whales, originally calling them “whale killers.” This term later evolved into “killer whale,” reflecting their status as apex predators. Their anatomical and genetic traits align them with other oceanic dolphins. Their placement within the Delphinidae family signifies a closer evolutionary relationship to other dolphins than to the larger baleen whales.
Key Distinctions
Despite their classification as dolphins, orcas possess several characteristics that distinguish them from their smaller dolphin relatives. Orcas are significantly larger than most other dolphins. Adult male orcas can reach 6 to 8 meters (20 to 26 feet) and weigh over 6 metric tons, while females are slightly smaller, ranging from 5 to 7 meters (16 to 23 feet) and weighing about 3 to 4 metric tons. In contrast, bottlenose dolphins average 2.5 to 4 meters (8 to 13 feet) in length and weigh between 150 to 650 kilograms (330 to 1,430 pounds).
Orcas have distinctive black and white coloration, with a black upper body and white undersides, along with white eye patches and a grey “saddle patch” behind their dorsal fin. Their dorsal fin is tall and prominent, especially in males, where it can reach up to 1.8 meters (6 feet) in height. Other dolphins typically have smaller, more curved dorsal fins. Orcas exhibit specialized hunting strategies, often working cooperatively in pods to pursue diverse prey, including fish, seals, sea lions, and other marine mammals. Their complex social structures, with some populations forming stable matrilineal family groups, are also a notable trait.