Sperm Whale | The Deep-Diving Giant of the World’s Oceans

Sperm whale

Physeter macrocephalus

Colossal giants with a taste for colossal squid, sperm whales are the largest of the odontocetes (toothed whales), and are found throughout the world’s oceans. The inspiration behind Moby Dick, these deep-diving behemoths take their name from spermaceti, a waxy, oil-like substance housed within their huge heads. Animals of extremes, sperm whales possess the largest brain on earth and produce the loudest sound of any animal! 

Physical characteristics of the sperm whale

Sperm whales are sexually dimorphic, exhibiting the greatest sexual difference among cetaceans; males are typically 30-50% longer than females, and can weigh up to three times as much. They are dark grey with wrinkled skin, short, wide pectoral fins and a low, thick, rounded dorsal fin positioned two-thirds along the back, followed by a dorsal ridge marked with a series of bumps known as knuckles, extending to the fluke. The fluke itself is large, broad, smooth and triangular. 

Their massive square-shaped heads account for roughly one-third of their total body length. The lower jaw is long and narrow, containing 52 cone-shaped teeth, while the upper jaw contains vestigial teeth that rarely erupt through the gums. A unique characteristic is the single blowhole, asymmetrically positioned on the left side of the head - an arrangement unique among cetaceans. White scars and scratches, particularly on the head, are commonly observed and are thought to result from encounters with their cephalopod prey.

• Size: ♂ 14 - 18 meters ♀10.5 - 11 meters

• Weight: ♂ 35 - 57 tonnes ♀15 - 20 tonnes

• Average Dive Depth:   600 – 1200 meters

• Average Dive Duration:   45 mins

• Life Expectancy:   60 - 70 years

Behaviour and life cycle

Sperm whales exhibit the largest geographical sexual segregation known in the animal kingdom, with males and females occupying largely separate ranges for most of their adult lives. Females and young males tend to remain in stable matrilineal groups in warm, low-latitude waters near the tropics, it’s thought their distribution roughly corresponds to sea-surface temperatures above 15°C. In contrast, mature males migrate to higher latitudes, and can be found from the tropics to the poles, younger males sometimes group together in “bachelor pods” when travelling to higher latitudes.

Mature males, which often live solitary lives or in bachelor groups, migrate from higher latitudes to tropical breeding grounds. Mating takes place in the warmer waters of the tropics; sperm whales exhibit a polygynous mating system; a mature male may mate with multiple females. Competition between rival males during the breeding season is intense, as they vie for access to receptive females. 

Following successful mating, females undergo a lengthily gestation period of 14 to 16 months. Calves are roughly 3.5 to 4.5 meters in length and weigh close to 1 tonne. Despite calves sampling solid food during their first year, they continue nursing for 4-5 years, with some individuals remaining dependent on their mothers for over a decade.

Conservation status

The International Union for Conservation of Nature (IUCN) currently classifies the sperm whale as vulnerable with the population trend currently unknown. 

Sperm whales face several major threats across their global range:

Vessel strikes: Vessel traffic worldwide is increasing, with an estimated 30,000 whales killed or injured annually with many strikes unreported. Sperm whales are especially vulnerable during the surface period between dives.

Entanglement: Marine debris such as, discarded ghost gear, rope and nets can entangle marine mammals causing injury, starvation or drowning. Deep-diving species are particularly at risk while foraging.

Noise Pollution: Anthropogenic (man-made) sound in the ocean is increasing, and can harm cetaceans. Impacts include masking of important sounds, altering behaviour, including vocalisations, temporary or long-term displacement, elevated stress, increased energy expenditure, and in severe cases, hearing damage or strandings. 

Climate change: Its thought that sperm whales are affected indirectly through shifts in ocean currents, productivity, and prey distribution. Warming oceans and overfishing could reduce foraging success, alter migration patterns, and lower reproductive rates.

Whaling: Commercial whaling heavily depleted sperm whale populations from 1800 to 1987, driven by demand for spermaceti oil, used in oil lamps, candles, and industrial lubricants. Sperm whales were also exploited for ambergris—a waxy substance formed in the intestines, used for centuries as a fixative to make fragrances last longer, giving rise to some of the earliest luxury perfumes. While large-scale whaling has mostly ceased following the global moratorium in 1986, small-scale subsistence hunting continues in a few regions.

How to photograph sperm whales?

Look for their large, dark bodies, wrinkled skin and low, rounded dorsal fin. In good conditions their distinctive, bushy blow, angled about 45 degrees forward and to the left can be clearly visible. As a whale prepares to dive, watch for the broad, triangular fluke lifting clear of the water, offering an excellent photo opportunity.

Where to see sperm whales in the wild?

Sperm whales are found worldwide, but sightings are more likely in deeper waters, especially near continental shelves. They are most abundant in warmer tropical regions, with only mature males migrating toward higher latitudes.

Sperm whales in the Arctic

In the Arctic, sightings of sperm whales are rare but possible, particularly of solitary males in the waters west of Svalbard. Encounters more often come in unexpected forms. In 2025, photographers documented a drifting sperm whale carcass in Arctic pack ice that attracted several polar bears. You can read more about this unusual encounter in the National Geographic story.

Sperm whales in Antarctica

The Antarctic encounters with sperm whales are extremely rare.