Sperm whales produce echolocation clicks almost continuously while foraging, which makes listening a good way to study them. Because sperm whales are more easily heard than seen, counts made by listening needed very little correction for whales missed under water.
Sperm whales make clicking sounds and use echolocation to find food. In echolocation, an animal makes a sound that travels through the water, bounces off an object and comes back as an echo.
Sperm whales are hard to count because they spend long periods under water and can be missed during sightings. Scientists pinpoint them by towing a hydrophone array and measuring the tiny time differences when a click arrives at each hydrophone.
Codas are stereotyped sequences of 3 to 40 broadband clicks. Sperm whales exchange codas when socialising or between long, deep foraging dives. Certain features of codas may be unique to each whale in a group, so individuals can be told apart.
A sperm whale can dive deeper than 3,000 feet (about 1,000 metres), and sperm whales often dive down to about 2,000 feet (600 metres). A sperm whale found tangled in a telephone cable at 1,300 metres depth helped scientists first understand how deep sperm whales dive.
Deep dives last about 45 minutes on average, although a sperm whale can stay underwater for an hour or more. A few dives go much further. As of November 2026, sonar has tracked sperm whales in dives deeper than 2,250 metres (1.4 miles), and the longest recorded dive for a sperm whale was more than 2 hours.
Scientists used digital tags to study 198 foraging dives by 37 sperm whales in the Atlantic Ocean, the Gulf of Mexico and the Ligurian Sea. An average dive cycle was a 45-minute dive followed by a 9-minute surface interval. Tagged sperm whales in the Gulf of America typically attempted 17 prey captures during each deep dive, counted from detected buzzes.
Sperm whales are usually found in water at least 1,000 metres deep. A sperm whale's ribcage is flexible, so its lungs can collapse safely under the water pressure of a deep dive. Its muscles hold extra myoglobin, a protein that stores oxygen.
A sperm whale eats mostly squid, and it eats about one ton of food in a day. A faecal sample study in the Galapagos found that 62% of the squid beaks belonged to the genus Histioteuthis, the cock-eyed squids.
The sperm whale is the largest of the toothed whales, but the blue whale and other large rorquals are bigger. An adult male is 49 to 59 feet (15 to 18 metres) long and can weigh up to 45 tons, and an adult female is up to about 40 feet long.
Adult male sperm whales usually live alone, except in the breeding season, and young males leave their family groups and live with other young males. Female sperm whales and their young travel together in groups, the females help look after the young together, and they stay in warm tropical waters all year.
Sperm whale hunting reached two peaks, one in the 1840s and one in the 1960s. Commercial whaling from about 1800 to the 1980s greatly reduced sperm whale numbers around the world, and the International Whaling Commission placed a moratorium on commercial whaling in 1986.
Underwater noise from human sources can interrupt the normal behavior of sperm whales, which rely on sound to communicate. Sperm whales can also become entangled in many different types of fishing gear, including trap lines, pots and gillnets.
As of November 2026, the sperm whale is listed as endangered under the Endangered Species Act in the United States and as vulnerable on the IUCN Red List. NOAA says sperm whale populations are still recovering and their numbers are likely increasing.
Words to know
- hydrophone: underwater microphone
- codas: click patterns
- echolocation: finding by sound
- sonar: sound tracking
- foraging: looking for food
