Sperm whales (Physeter macrocephalus) are the largest toothed whale species.
Sperm whales are found in all oceans. They prefer ice-free waters over 1,000 meters (3,300 ft) deep.
Although both sexes range through temperate and tropical oceans and seas, only adult males populate
higher latitudes.
The sperm whale has an average lifespan of 70 years.
Mature males average 16 meters (52 ft) in length and weigh about 41,000 kilograms (45 short tons); but some may reach 20.5 meters (67 ft), and weighing up to 57,000 kilograms (63 short tons).
Mature females average 11 meters (36 feet) in length and weigh about 13,600 kilograms (15 short tons).
The sperm whale is distinguished by its extremely large head, which takes up to 25 to 35% of its total body length.
Sperm whales are mostly dark gray, but oftentimes the interior of the mouth is bright white, and some
whales have white patches on the belly.
Their flippers are paddle-shaped and small compared to the size of the body, and their flukes are very
triangular in shape. They have small dorsal fins that are low, thick, and usually rounded.
The sperm whale’s lower jaw is very narrow and underslung. The sperm whale has 18 to 26 teeth on each side of its lower jaw which fit into sockets in the upper jaw. The teeth are cone-shaped and weigh up to 1 kilogram (2.2 lb) each.
Sperm whales have the largest brain of any animal (on average 7.8 kilograms (17 pounds) in mature
males), however, compared to their large body size, the brain is not exceptional in size.
It is the only living cetacean that has a single blowhole asymmetrically situated on the left side of the head near the tip.
Sperm whales make some of the longest dives achieved by mammals, with some lasting up to 90 minutes.
Capable of plunging to 2,250 meters (7,382 feet), it is the second deepest diving mammal, following only the Cuvier’s beaked whale.
A Sperm Whale’s normal cruising speed ranges somewhere around 5 to 15 km/h (3 to 9 mph). When they speed up they can swim at approximately 35 to 45 km/h (22 to 28 mph), maintaining that speed for about an hour.
Because sperm whales spend most of their time in deep waters, their diet consists of many larger
organisms that also occupy deep waters of the ocean. Giant squid comprise about 80% of the sperm whale diet and the remaining 20% is comprised of octopus, fish, shrimp, crab and even small bottom-living sharks.
Sperm whales use echolocation mainly for navigation and hunting. Echolocation allows sperm whales to “see” by interpreting the echoes of sound waves that bounce off of objects near them in the water. It provides sperm whales a way to gather information about objects and prey around them including their range and configuration.
Sperm whales have disproportionately small eyes so it is thought that they do not see particularly well. In fact, blind sperm whales have been captured in perfect health with food in their stomachs. Instead of sight, sperm whales are thought to use echolocation to seek their prey and navigate the topography of their environment. Sperm whale hearing abilities are not well known.
For some time researchers have been aware that pods of sperm whales may sleep for short periods, assuming a vertical position with their heads just below or at the surface.
Sperm whales communicate through Morse-code-like patterns of clicks called “codas,” which are different than the echolocation clicks they emit to find prey. Geographically separate pods exhibit
distinct dialects.
The sperm whale is the world’s loudest animal: its communicative clicks have been measured at 230 decibels (dB).
How sperm whales choose mates has not been definitively determined. Males will fight with each other over females, and males will mate with multiple females, making them polygynous, but they do not dominate the group like a harem.
The gestation period is 14 to 16 months. Birth is a social event, as the mother and calf need othersto protect them from predators.
Females and young males live together in groups while mature males live solitary lives outside of the mating season. The females cooperate to protect and nurse their young. Females give birth every four to twenty years, and care for the calves for more than a decade.
The most common natural predator of sperm whales is the orca, but pilot whales and false killer whales sometimes harass them. Orcas prey on target groups of females with young, usually making an effort to extract and kill a calf. The adults will protect their calves or an injured adult by encircling them.
The sperm whale was named for the valuable spermaceti oil (wax) that this whale produces in the spermaceti organ (located in its head). A sperm whale’s spermaceti organ may contain as much as 1,900 liters (500 gallons) of substance. Spermaceti was used chiefly in ointments, cosmetic creams, fine wax candles, pomades, and textile finishing; later it was used for industrial lubricants.
Ambergris is a solid waxy waste product from its digestive system. It is still highly valued as a
fixative (allowing the scent to last much longer) in perfumes and other uses.
The sperm whale’s ivory-like teeth were often sought by eighteenth- and nineteenth-century whalers,
who used them to produce inked carvings known as scrimshaw.
Currently the Endangered Species Act and the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), prevents the sales of or trade in sperm whale ivory harvested after 1973 or scrimshaw crafted from it.
Whaling fleets killed an estimated 1 million sperm whales between the 18th and 20th centuries.
The IUCN Red List of Threatened Species lists the sperm whale as being “Vulnerable.”
The total number of sperm whales in the world is unknown, but is thought to be in the hundreds of
thousands.
The White Whale hunted in Herman Melville’s novel Moby Dick (1851) is presumably an albino sperm whale.
Sperm whales are not the easiest of whales to watch, due to their long dive times and ability to travel long distances underwater. However, due to the distinctive look and large size of the whale, watching is increasingly popular.