Head to head
Sperm Whale vs Blue Whale
The sperm whale and the blue whale are the record holders of the whale world, but for different titles. The blue whale is the largest animal known to have ever existed, anywhere, ever. The sperm whale is the largest predator with teeth, and the largest toothed whale by a wide margin. They also feed, dive, and sound completely differently.
| Sperm Whale | Blue Whale | |
|---|---|---|
| Type of whale | Toothed whale (largest of them) | Baleen whale |
| Length | About 16 to 18 m (males); females smaller | About 24 to 30 m |
| Weight | About 35 to 45 tonnes | About 130 to 150 tonnes, sometimes more |
| Feeds on | Squid and deep-sea fish, hunted individually | Krill, filtered by the tonne |
| Diving | Routinely 1,000 m, sometimes over 2,000 m, up to an hour or more | Usually shallow, to about 100 to 200 m while feeding |
| Head | Huge and square, about one third of body length | Broad and U-shaped, a small fraction of body length |
| Sound | Loud echolocation clicks, the loudest of any animal | Very low-frequency moans carrying hundreds of kilometres |
| Conservation status | Vulnerable | Endangered |
Sperm Whale vs Blue Whale: common questions
Which is bigger, a sperm whale or a blue whale?
The blue whale, clearly. A large blue whale reaches about 30 m and 150 tonnes, while a big male sperm whale is around 18 m and 45 tonnes, so the blue whale is roughly three times the mass. The blue whale is in fact the largest animal known ever to have lived, heavier than the biggest dinosaurs. The sperm whale holds a different record: it is the largest toothed predator on Earth and the largest of the toothed whales, a group that also includes dolphins and orcas. Female sperm whales are much smaller than males, only around 11 m, which adds to the size gap when comparing typical individuals.
Why does the sperm whale have such a huge head?
The head is essentially a giant sound machine. It houses the spermaceti organ and a structure called the junk, a stack of lenses of oil and connective tissue, through which the whale focuses intense clicking sounds. Air is forced past a valve at the front of the head to make a click, which bounces around inside the organ and is beamed forward as a powerful, directional pulse used to locate and possibly stun squid in deep, dark water. The oil may also help the whale adjust its buoyancy for deep dives by changing temperature. The spermaceti was what whalers were after, since it burned with a bright, clean flame and made fine candles and machine oil.
How did whaling affect each species?
Both were hunted heavily, at different times. Sperm whales were the target of the classic open-boat whaling of the 1700s and 1800s, immortalised in Moby-Dick, pursued for spermaceti and oil, and later by industrial fleets into the 20th century; total kills ran into the hundreds of thousands, but the species held on and is now considered Vulnerable and slowly recovering. Blue whales were largely out of reach until fast steam catchers and explosive harpoons arrived around 1900, after which they were killed on an enormous scale, an estimated 340,000 in the Southern Hemisphere alone, until protection came in 1966. Some blue whale populations remain at a small fraction of their original size and the species is still listed as Endangered.