Names: Sperm Whale, Cachelot, Pot Whale
Appearance: Dark grey, sometimes bears white patches on belly
Weight: Up to 15 tons for females; 45 tons for males (30,000 - 90,000lbs.)
Size: 36 - 52 ft. in length
Lifespan: At least 30-50 years in the wild
Family: Physeteridae
Genus: Physeter
Type: Mammal
Similar to many cetacean species, female Sperm Whales will typically form lasting bonds with other females in their family. On average, up to 12 females and their young will form a family unit. Females usually stay with their family unit their entire lives, while males will often leave the pod anywhere between 4 and 21 years old. They can be found in "bachelor schools", consisting of other males that are about the same age and size. As the males get older, they begin to migrate to higher latitudes (toward the poles) and the bachelor schools will generally become smaller and smaller until the largest males end up alone.
Because Sperm whales spend a majority of their time in deep waters, their diet consists of large organisms that also occupy deep waters. Their preferred prey are large squid that often weigh between 3.5 ounces up to 22 pounds; though they also prey on sharks, skates, and other fish. An average dive lasts around 35 minutes and usually reaches to 1,312 ft. However, these whales have the capacity to dive for over an hour to depths exceeding 3,280 ft.
Their bodies have specifically evolved to be able to handle these long dives. Their flexible ribcage allows lung collapse, reducing nitrogen intake; and their metabolism can decrease to conserve oxygen.
However, repeated dives to great depths have shown long-term effects in some whales. Bones belonging to some whales show the same pitting that typically signals "the bends", or decompression sickness in humans; a condition in which nitrogen that is absorbed into the body during a dive is released too quickly during the ascent to the surface.
Sperm whales have about 20-26 large conical teeth in each side of the lower jaw. Teeth in the upper jaw rarely emerge and have often been considered to be vestigial, as they do not appear to be necessary for feeding.
Females typically reach sexual maturity somewhere around 9 years old when they are about 29ft. long. They endure a 14-16 month gestation period and typically give birth once every 5 years. Even though calves will begin eating solid food before they reach 1 year of age, they will continue to suckle from their mother for several years.
For male Sperm Whales, puberty is prolonged and typically lasts between 10 and 20 years old. While they are sexually mature at this time, they often will not actively participate in breeding until they reach their late twenties. Males reach physical maturity around 50 years old and often grow as long as 52ft. long.
Sperm Whales are very unique in the fact that they have the largest brain known of any modern or extinct animal. Their melons, or heads, are also home to a large complex of organs. These organs are filled with a liquid mixture of fats and waxes called spermaceti. The function of this organ is not entirely known, but it may serve as a tool to generate powerful and focused echolocation, or it may serve as a cooling organ to diminish the whale's volume and it's buoyancy during deep dives.
In Herman Melville's classic fictional novel Moby Dick, it suggests that the Sperm Whales' melon serves as a kind of battering ram in fights between males. Apart from the well-documented sinking of the ships Essex and Ann Alexander, the hypothesis that Sperm Whales use their melons in this way is not well-supported in current scientific literature.
In the eighteenth, nineteenth, and twentieth centuries, Spermaceti and sperm oil were much sought after by whalers. These substances were used in a variety of commercial applications, including candles, soap, cosmetics, machine oil, other specialized lubricants, lamp oil, pencils, crayons, leather waterproofing, rust-proofing materials, and many pharmaceutical compounds. Ambergris, a solid, waxy and flammable substance produced in the Sperm Whales digestive system, was also sought after as a fixative in perfume.
The ivory-like teeth of Sperm Whales was also sought after by 18th and 19th-century whalers, who used them to produce inked carvings known as scrimshaw. However, the demand for this ivory declined significantly after the retirement of whaling fleets in the 1880's, though whaling continued in pursuit of Spermaceti and sperm oil.
From 1941 to 1943 during WWII, Norwegian expeditions reportedly took over 3,000 Sperm Whales off the coast of Peru alone. Whaling continued and reached it's peak in the 1960's until whaling reportedly led to the near extinction of large whales, including Sperm whales.
In 1972, a ban on whale oil use was instituted and The International Whaling Commission gave Sperm Whales full protection in 1985; though hunting by Japan in the northern Pacific continued until 1988.
During the whaling era, NOAA estimates that around 1 million Sperm Whales were taken. While they suffered a hard blow, they are currently only listed as vulnerable by the IUCN Red List of Threatened Species. The recovery from the whaling years is a slow process, particularly in the south Pacific, where the toll on breeding-age males was severe.
Today, there are no good estimations regarding current population numbers, but the best possible estimate researchers have puts Sperm Whales between 200,000 and 1,500,000 individuals worldwide.
While the threat of being killed by whalers is no longer an issue, Sperm Whales still face a variety of threats; both natural and man-made.
Natural threats include being killed by Orcas, who have been documented hunting Sperm Whales on at least one occasion in California, though it is believed that most attacks from Orca are generally unsuccessful. Some large sharks may also be a threat, especially to young whales.
Man-made threats are more prominent. Some whales become victim to ship strikes which may cause permanent damage or death. Noise pollution, especially in areas where shipping and both oil and gas activities are high. However, the effects of noise on Sperm Whales is uncertain. Some studies suggest the whales may be highly sensitive to noise while other studies have found little to no effect; to date, all published studies have focused on short-term behavioral effects. It has been observed that Sperm Whales will avoid areas of sonar and seismic surveys, but no mortality has been documented.
Fishing gear, while not as big a threat as others, has still resulted in some fatalities. Other cetaceans that remain closer to the shore have higher rates of injury or death in run-in's with fishing gear. In particular, gillnets have been a problem with Sperm Whales in the Mediterranean Sea. Some whales will take fish off fishing gear, such as demersal long-line gear, in an activity known as "depredation". Depredation of long-line catches seems to be a recent and growing phenomenon and has been observed in many regions. This behavior has resulted in reported entanglements and deaths, but has also caused hostility from some fishermen - including shooting of whales.
Pesticides and other chemical pollutants are also a threat to Sperm Whales. Tissue samples taken have revealed high-levels of contaminants such as polycholorobiphenyls (PCBs), chlorinated pesticides (DDT, DDE, etc.), polycyclic aromatic hydrocarbons (PAHs), and heavy metals. However, any population-level effects on health are unknown.
Sperm Whales have also had a short encounter with captivity in the past; though not much is known about each specific whale. According to the website Ceta-Base, two young Sperm Whales were rescued and taken in by the Miami Seaquarium after becoming stranded.
The first whale, apparently named Peanut, was brought to the Seaquarium on July 31, 1964. Unfortunately, it died on August 3, little more than three days after being rescued.
In January of 1989, a calf beached itself and was also rescued by the Seaquarium. However, Ceta-Base does not list this rescue, so it is unknown if this calf was a Sperm Whale or a Dwarf or Pygmy Sperm Whale. However, this calf was unable to make it more than 24hrs. and died the morning following it's rescue.
Finally, on December 10, 1992, another whale beached itself and was taken to the Seaquarium. This calf managed to live a total of 11 days, and even allowed divers to enter it's tank. The calf, unfortunately, died on December 21, 1992.
Sources:
National Geographic
NOAA
Wikipedia
IUCN Red List of Threatened Species
American Cetacean Society
MarineBio.org
The Marine Mammal Center
Ceta-Base
Sun Sentinel
CetaGifs
Sperm Whale birth
"What is..." series:
Killer Whale | Narwhal | Beluga Whale | Pilot Whale | Risso's Dolphin | Bottlenose Dolphin | Vaquita | South Asian River Dolphin | Humpback Whale | Atlantic Spotted Dolphin
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