Sperm Whale

Found in all of the world’s oceans, sperm whales were once hunted extensively; a moratorium on commercial whaling in 1986 has allowed sperm whale populations to begin recovering, though they remain classified as Vulnerable and their numbers are still well below pre-whaling levels. Despite their colossal size, sperm whales can move at speeds of up to 23 miles per hour and dive to depths as far as 10,000 feet.

5 Incredible Sperm Whale Facts

• When diving for food, these whales can hold their breath for up to 90 minutes at a time.
• Their massive tail fluke, measuring an average of 16 feet from end to end, allows them to travel in bursts of up to 23 miles per hour.
• Two other species of sperm whale exist but are relatively unknown — the pygmy sperm whale and the dwarf sperm whale.
• These whales will dive up to 3,280 feet to find food, and their skeletons show pitting that may be indicative of decompression sickness.
• Female sperm whales form lasting bonds with other females, forming social units that often last entire lifetimes.

Classification and Scientific Name

Sperm whales belong to the class Mammalia, the order Cetacea, the family Physeteridae, and the genus Physeter. The scientific name for this cetacean is Physeter macrocephalus; the word Physeter is derived from a Greek word that means “blower,” which refers to the whale’s blowhole. The word macrocephalus means “big-headed,” which refers to the creature’s massive head, which makes up nearly one-third of its skeleton. This whale is also known by the specific name Physeter catadon; the word catadon means “down tooth,” which refers to the fact that only the bottom teeth erupt while the top remains beneath the gums.

The sperm whale is also called a cachalot, which may be derived from an archaic French term meaning “big teeth” or a Portuguese word meaning “big head.”

Evolution

During the middle of the Miocene epoch, around 12 million years ago, two giant predators roamed the seas. Megalodon was the ancient ancestor of the shark — a much bigger, more vicious version of the great white shark of today. The other gargantuan killer was the ancestor of the sperm whale, Livyatan melvillei, about the same size as the modern bull sperm whale — but with one of the largest bites in the history of life on earth.

Livyatan’s giant head and mouth had evolved to equip the animal with the bite needed to capture, kill, and consume baleen whales — its main source of food. Scientists believe that Livyatan and Megalodon were as important to Miocene marine ecosystems as orcas and great whites are today. Present-day sperm whales retain the giant head and teeth, as well as the organ referred to as spermaceti — an oil-filled sac prized by whalers. Its purpose in Livyatan and in sperm whales is still unknown.

Species

This whale is the only living member of the genus Physeter, and it is one of three living species in the sperm whale family, Physeteridae. The other two species in that family are the pygmy sperm whale, Kogia breviceps, and the dwarf sperm whale, Kogia simus. Reminiscent of dolphins, pygmy and dwarf sperm whales measure between 8 and 13 feet long and feature grey bodies and white bellies.

Appearance

The largest toothed predators on earth, these whales grow to a size of 49 to 59 feet in length and between 35 and 45 tons in weight. Males grow to an average size of 52 feet and 45 tons, while females grow to an average of 40 feet and 15 tons. Their massive heads — their skulls make up about one-third of their skeletons — feature prominent, rounded foreheads and narrow lower jaws. The head houses the largest brain of any creature on earth — it weighs up to five times more than a human brain — along with large quantities of spermaceti, an oily fluid that turns waxy when cold. Once thought to be sperm, the substance remains somewhat mysterious to scientists. Some believe that spermaceti may help these whales alter their buoyancy for more effective diving, but its exact purpose is unclear.

The skin behind the head is normally wrinkled, and the skin across the body is typically dark grey; some whales have white patches on their bellies.

This whale is the only living creature with a single, asymmetrical blowhole, which is found on the left side of the crown of its head. The interior of their mouths is usually bright white, and 20 to 26 large teeth are found on either side of the lower jaw; the teeth along the top rarely erupt from the gums. Sperm whales have paddle-shaped flippers, small dorsal fins, and small, triangle-shaped flukes. However, its tail fluke can measure up to 16 feet long from tip to tip, allowing it to travel in short spurts at speeds of up to 23 miles per hour.

Distribution, Population, and Habitat

Sperm whales have one of the broadest global populations of any marine animal species. Heavily targeted by whalers primarily during the 18th and 19th centuries, their population declined drastically until a moratorium was called in 1986 by the International Whaling Commission. Since then, it is believed that their population levels have increased again. No official accounting is available, but it is estimated that there are anywhere from 300,000 to 450,000 sperm whales in the world today. This whale is classified as Vulnerable by the IUCN.

These toothed predators are found in all of the world’s oceans. However, their populations tend to be found primarily in waters near Alaska, New England, the Mid-Atlantic, the West Coast, and the Pacific Islands.

Predators and Prey

While they don’t face much in the way of natural predators, these whales face numerous threats that are mostly caused by humans. These include becoming entangled in fishing gear, vessel strikes, marine debris, oil spills, and other types of contamination. Noise pollution from ships and other human activities interrupts their behavior and may impact their survival. Climate change is increasingly recognized as a significant threat to sperm whales, alongside other major threats such as ship strikes, entanglement, and pollution.

What Eats Sperm Whales?

These whales do not face any true predators in the wild. However, young or injured whales may be hunted by killer whales or orcas.

What Do Sperm Whales Eat?

As carnivores, sperm whales’ diets consist almost entirely of other creatures. They mostly target larger species, and their diets are mostly made up of sharks, skates, squid, and fish. They can eat up to one ton, or between 3 and 3.5 percent of their body weight, per day.

Reproduction and Lifespan

The average lifespan for these whales is around 60 years. Female whales and young male whales live together in pods of between 15 and 20 individuals, while mature male sperm whales tend to travel solo or move from group to group.

Females and young males stay in tropical and subtropical waters throughout the year, and they are believed to engage in communal childcare. However, males tend to migrate toward higher latitudes alone or in groups before returning toward the equator to breed. Female sperm whales reach sexual maturity at around nine years of age or about 29 feet in length; they reach physical maturity at around 30 years or about 35 feet in length. Females produce one calf every five to seven years, on average. After a gestation period of 14 to 16 months, a calf measuring an average of 13 feet in length is born. They can start eating solids at around one year of age, but they often continue nursing for many years.

Male sperm whales stay the same size as females for roughly the first 10 years of life. However, they continue to grow substantially until well into their 30s. They reach sexual maturity in their late 20s and physical maturity at about 50 years, or at about 52 feet in length. Males typically leave their pods between the ages of four and 21 years; they often join “bachelor schools” made up of other males around the same size and age. As they age, they start migrating toward the poles, making trips back to tropical waters to breed.

Sperm whales are known for being vocal, and they make lots of sounds. Indeed, their sounds can measure up to 530 decibels. Sometimes, they make sounds to communicate; other times, they do so for echolocation purposes.

The average lifespan for a sperm whale is about 60 years.

Whale Oil

Sperm whales were once hunted extensively for their spermaceti, which was used in candles, oil lamps, and as a lubricant. They were also targeted for their ambergris, which is believed to develop in their stomachs around squid beaks, which was used — and still is used — in perfumes. However, a moratorium on commercial whaling was enacted in 1986, though some countries continue limited whaling under objections or reservations. They have never been popularly consumed as food.