Do Sperm Whales Fight Giant Squid? What the Evidence Shows

What is the evidence that sperm whales eat giant squid?

The strongest evidence is the squid beak. Like all squid, the giant squid has a hard, parrot-like beak that a sperm whale cannot digest. Beaks pile up in the whale’s stomach, sometimes by the thousands, and scientists can identify the squid species from the beak’s shape and estimate the squid’s size from its dimensions.

Giant squid beaks, and sometimes whole arms, tentacles and large pieces of body, have been found in sperm whale stomachs from many parts of the world, especially from the North Atlantic, South Africa, Japan and New Zealand. Much of what is known about deep-sea squid in general first came from whale stomachs. The colossal squid, for example, was described in 1925 from two arm crowns found inside a sperm whale.

Using beak counts and the size of the sperm whale population, researchers have estimated that sperm whales eat somewhere between a few million and over a hundred million giant squid a year. The enormous range shows how uncertain the numbers are, but it suggests that giant squid are far more common than sightings would suggest.

What do sucker scars on sperm whales tell us?

Many sperm whales have round scars on their heads and around their mouths. They match the suckers of large squid. Each giant squid sucker is a cup 2–5 cm (0.8–2 in) across with a ring of sharp, finely toothed chitin, which can cut the skin as a captured squid grips the whale’s head.

The scars show that squid fight back as they are caught, but they also show that the whales survive these encounters. In the Antarctic, some sperm whales carry long scratches thought to come from the swiveling hooks of the colossal squid, compared in giant squid vs colossal squid.

Some old stories describe sucker scars as wide as dinner plates, implying squid of impossible size. No such suckers are known from any squid. One common explanation is that small scars made on a young whale stretch as the whale grows, and some marks may have other causes.

Why has no one filmed a fight?

Sperm whales hunt in total darkness, usually 400–1,200 m (1,300–3,900 ft) below the surface, on dives that last about 45 minutes. Giant squid live mainly at about 300–1,000 m (1,000–3,300 ft). Getting a camera into that darkness, at the right moment, next to a fast-moving whale is extremely difficult.

Scientists have tried. In the late 1990s, expeditions off Kaikōura, New Zealand, attached small video cameras to sperm whales in the hope of filming a squid hunt, without success. Japanese researchers who took the first photographs of a live giant squid in 2004 found it by working in a known sperm whale feeding area off the Ogasawara Islands, using the whales as a guide to where the squid lived. The full story is in has anyone filmed a live giant squid?

Tags that record sound now show when a sperm whale attacks prey. Its search clicks speed up into a rapid buzz, or creak, as it closes in. A tag cannot say which squid was caught, though, and so far no camera has captured the moment.

How much of their diet is giant squid?

Less than the legend suggests. In most studies, the bulk of a sperm whale’s diet is medium-sized deep-sea squid. Around the Galápagos Islands, for example, the squid most often eaten weighed roughly 12–650 g (0.4 oz–1.4 lb). Sperm whales also eat octopuses, deep-sea fish, rays and sharks.

Giant squid usually make up only a small share of the beaks found in sperm whale stomachs. Because each one is so heavy, though, a few giant squid can provide a large meal. A sperm whale eats about 3–3.5% of its body weight a day, which for a 45-tonne male is well over a tonne of food.

Is it a fair fight?

Not at all. The two animals look similar in length, but the comparison is misleading.

Even the largest giant squid weighs less than 1% as much as an adult male sperm whale. Most of the squid’s length is in two long, thin feeding tentacles. The whale has the size, the speed in a short chase and a sonar system that can find prey in the dark.

How exactly a sperm whale catches large squid is still unknown. Well-fed whales have been found with broken or deformed jaws, which suggests they may suck prey into the mouth rather than relying on their teeth.

Where did the battle legend come from?

Whalers saw squid remains vomited up by dying or harpooned whales and imagined the struggle behind them. Frank Bullen’s 1898 book The Cruise of the Cachalot described a moonlit fight between a sperm whale and a huge squid at the surface, an account that has been retold many times but never confirmed.

The idea stuck. Novels, films and a famous diorama of a sperm whale and giant squid at the American Museum of Natural History in New York all show the two locked in combat. Older tales of sea monsters may also have grown from sightings of whales and squid, as described in Is the kraken real? The real story is quieter but no less remarkable: a predator hunting by sound in total darkness, a kilometer below the surface.