Head to head
Whale vs Dolphin
Asking whether an animal is a whale or a dolphin is a bit like asking whether a spaniel is a dog or a spaniel. Dolphins are one branch of the whales, so the useful question is which kind of whale you are looking at.
| Whale | Dolphin | |
|---|---|---|
| Relationship | The whole order Cetacea | The small toothed whales within it |
| Teeth or baleen | Baleen whales have neither teeth nor echolocation | Always teeth, always echolocation |
| Typical size | Up to 30 m and 180 t (blue whale) | Mostly 1.5 to 4 m; orca to ~9 m |
| Feeding | Filter-feeding in baleen whales; hunting in toothed | Active hunting of fish and squid |
| Social life | Varies; many baleen whales fairly solitary | Highly social, in pods, often lifelong bonds |
| Echolocation | Toothed whales yes; baleen whales no | Yes, highly developed |
| Number of species | Around 90 in the whole order | Around 40 oceanic dolphins plus river dolphins |
| The odd one out | "Whale" is a size label, not a branch | The killer whale is the largest dolphin |
Whale vs Dolphin: common questions
Is a dolphin a type of whale?
Yes. Dolphins belong to the toothed whale group within the order Cetacea, so biologically every dolphin is a whale, in the same way every terrier is a dog. The word whale is used loosely for the larger cetaceans and dolphin for the smaller, sleeker, more social toothed ones, but there is no scientific line dividing them, and some animals sit awkwardly across it. The killer whale and the pilot whales, for instance, are called whales because of their size but are members of the dolphin family, Delphinidae. Porpoises are a separate small family, also within the toothed whales.
How can you tell a whale from a dolphin at sea?
Size and shape are the quickest guides. A dolphin is usually small, under about 4 metres, with a streamlined body, a distinct beak, a curved or hooked dorsal fin, and an energetic, acrobatic swimming style that often brings it right up to a boat's bow wave. A large whale shows a broad back, a small or absent dorsal fin far down the body, a blow that hangs in the air, and slow, deliberate surfacing, and it typically travels alone or in small loose groups rather than a leaping pod. The blow shape helps too, a tall single or bushy V-shaped spout for the great whales versus a low, quickly vanishing puff for dolphins.
Which is more intelligent, a whale or a dolphin?
Both groups contain animals with very large, complex brains, and comparisons are difficult. Bottlenose dolphins are among the most-studied and score highly on almost every cognitive test used for animals, passing mirror self-recognition, using tools, learning symbolic communication, and maintaining lifelong social relationships and individual signature whistles. Sperm whales and killer whales, both toothed whales, have the largest brains of any animal and show sophisticated culture, with distinct clan dialects and hunting traditions passed down through generations. The baleen whales are less studied but produce long, structured songs that change and spread between populations. There is no clear winner; the toothed whales, dolphins included, are simply among the most cognitively capable animals on Earth.