A group of common dolphins breaking the ocean surface

Whales, dolphins and porpoises

Whales, dolphins and porpoises belong to the order Cetacea. These are aquatic mammals that have streamlined bodies highly evolved for swimming. Their hind limbs have become vestigial as part of this streamlining. All whales, dolphins and porpoises are cetaceans, including the biggest animal ever to have lived - the blue whale.

Scientific name: Cetacea

Rank: Order

Common names:


Explore this group

Prehistoric life

Whale and dolphin size range

A graphic illustration comparing the size of whales and dolphins with humans, from largest to smallest: blue whale, sperm whale

A comparison of whale and dolphin size in relation to humans - from the 30m long blue whale to the 2.5m long harbour porpoise.


  1. Life
  2. Animals
  3. Vertebrates
  4. Mammals
  5. Cetartiodactyla
  6. Whales, dolphins and porpoises