A sperm whale headbutt has been captured on camera for the first time. The fearsome headbutts that sank whaling ships in the 19th century and even inspired novels have been confirmed as natural whale behavior rather than sailors' tall tales. Why whales headbutt each other remains unknown. Scientists plan to determine through further research whether it is a form of play that strengthens social bonds or an intense dominance contest among males.
A team led by Alec Burslem of the University of St Andrews said in Marine Mammal Science on the 23rd that it filmed sperm whales bumping heads with drones between 2000 and 2002 in the North Atlantic around the Azores and the Balearic Islands. This is the first scientific confirmation of sperm whale headbutting.
◇First sighting of the heading that sank whalers
The sperm whale is a large whale measuring 15 meters long and weighing up to 50 tons. It is the largest of the toothed whales that bite prey with teeth, such as orcas and dolphins. Its brain volume is by far the largest among whales. Since the 19th century, sperm whales have been known as terrifying animals that ram and sink ships. The protagonist of Herman Melville's 1851 novel Moby-Dick is a sperm whale.
The St Andrews team worked with the University of the Azores in Portugal and Association Tursiops, a Spanish whale research institute, to track sperm whales in the North Atlantic with drones. After three years, they captured three cases of sperm whales ramming each other. Two appear to have been collisions between individuals believed to be juvenile males, and in one case a male rammed a female's torso with his head.
The impulse was greatest in the case where a male struck a female, at 200 kilonewtons. The female's body midline was visibly displaced. A newton is the force required to accelerate a 1-kilogram mass by 1 meter per second squared. Considering that the impact when a 1.5-ton car hits a wall at 100 kilometers per hour is about 41 kilonewtons, you can imagine how powerful a sperm whale's heading is. It is strong enough to sink a ship.
In fact, the American whaling ship Essex, a 27-meter sailing vessel, sank in the South Pacific on Nov. 20, 1820, after being attacked by a sperm whale. The incident inspired Moby-Dick. According to records left by the first mate at the time, the sperm whale charged from 500 meters away at twice its usual speed and rammed the ship. There were several other cases of sperm whales sinking vessels besides the Essex.
The researchers did not clearly determine why sperm whales headbutt. There are two hypotheses. One is male–male competition. In fact, most of the whales that headbutted in this study were males. However, headbutting may not have been advantageous in evolution for whales. That is because whales emit ultrasound from the head to locate themselves and communicate with companions.
Another possibility is that whales headbutt as play. It may be a process of practicing and preparing for competition, courtship, and sexual behavior that young whales will face as they grow. This is behavior commonly seen in other mammals.
In fact, when juvenile males headbutt, exposing the genitals has also been observed, suggesting a possible sexual context. The researchers said more observation is needed to understand why sperm whales headbutt. Fortunately, unlike in the past, the emergence of new technology such as drones is expected to yield more observations.
◇A mysterious animal that sleeps upright
Sperm whales are an endangered species whose numbers have plummeted due to indiscriminate overhunting to obtain ambergris and whale oil. Ambergris is an intestinal secretion from sperm whales that clumps and is expelled, and it was used as a fixative for high-end perfumes. In the 18th century, more than 1.1 million sperm whales lived worldwide, but with the rise of commercial whaling, their numbers are estimated to have fallen to 29% by 1880.
To save sperm whales, we must first know what kind of animals they are. Yet despite their enormous size, much remains unknown. One representative behavior is sleeping while upright with the head pointed toward the surface. Whales and dolphins are known to keep one hemisphere of the brain awake even when sleeping. They do not fall into deep sleep in case predators approach. They keep one eye open, swim, and breathe. But sperm whales showed no movement as the entire brain entered complete rest.
A team led by Patrick Miller of the University of St Andrews first reported in 2008 in Current Biology that sperm whales sleep upright. Observations showed that sperm whales descend vertically from the surface, then reverse direction by 180 degrees and drift upward with their heads toward the surface, relaxing their entire bodies as they fall asleep.
The time spent sleeping upright was very short. Measuring their sleep showed it accounted for only 7.1% of total time. It ranged from as little as 6 minutes to as long as 24 minutes. This is far shorter than the 32% for belugas and 42% for gray whales. The researchers suggested that with the entire brain in complete deep sleep, they may be able to recover their energy in a short time.
References
Marine Mammal Science (2026), DOI: https://doi.org/10.1111/mms.70153
Current Biology (2008), DOI: https://doi.org/10.1016/j.cub.2007.11.003