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Sperm whales (Macrocephalic physeter) are the largest toothed whales, with huge square heads and the largest brain of any animal on Earth. These deep divers are known to stalk giant squids and other prey up to 3 kilometers below the ocean’s surface.
Sperm whales are the only living species of the genus Physete and are more closely related to dolphins than to baleen whales, such as blue whales. The name sperm whale comes from the early whalers who confused the waxy oil found in the spermaceti organ of a sperm whale’s head with sperm, according to the Zoological Society of London (ZSL).
HIGHLIGHTS
Cut: Up to 59 feet (18 meters) long
Lifetime: Potentially over 70 years
Conservation state: Vulnerable
According to the National Oceanic and Atmospheric Administration (NOAA), humans hunted sperm whales extensively in the 1800s and 1900s for their spermaceti oil to use in oil lamps and other products.
Whaling is now banned in most countries and the trade has largely ceased. However, the sperm whale population has yet to recover from whaling and remains vulnerable to extinction, according to the International Union for the Conservation of Nature (IUCN).
Related: Sperm whales outsmarted 19th century whalers by sharing escape tactics
How big is a sperm whale?
Male sperm whales can grow up to 59 feet (18 meters) long and weigh up to 62.8 tons (57 metric tons). Females are smaller and are no more than 11m in length and weigh up to 16.5 tonnes (15 metric tonnes), according to the Whale and Dolphin Conservation (WDC) charity.
The head of a sperm whale is about a third of its total body length. Whales have a distinctive, narrow lower jaw that contains all of their teeth. Sperm whale teeth are cone-shaped and can be up to 7.9 inches (20 centimeters) long and weigh 2.2 pounds (1 kilogram) each, according to the BC Cetacean Sightings Network, a research and conservation in Canada.
Related: Rare sperm whale fossils shed light on mysterious family tree
Where do sperm whales live?
Sperm whales live in oceans around the world and their geographic range covers almost all marine waters that are deeper than about 3,280 feet (1,000 m) and not covered with ice, according to the IUCN.
Age, sex, food availability, and other factors influence where sperm whales live and travel, but their migration is not as predictable or well understood as that of other whale species. Mature males can undertake long migrations in cooler waters to the poles for better food sources, while females and their young remain in warmer tropical waters year-round, according to NOAA.
Social life and breeding
Sperm whales are social animals and use a range of vocalizations to communicate with each other, including clicks and whistles. They often live in groups of around 30 individuals, but group size varies and some individuals live solitary. The most common types of groups are preschool groups, made up of mature females and their juvenile offspring; and singles groups, made up of sexually inactive men. Mature males typically live alone, according to the University of Michigan’s Animal Diversity Web (ADW).
THE TAXONOMY OF CASHMERE
Kingdom: Animalia
Phylum: Chordata
To classify: Mammals
Order: Cetaceans
Family: Physeteridae
Genus & Species: Macrocephalic physeter
Source: SITI
Mature migrating males usually return to tropical waters in the spring to mate with the females. After mating, females have a gestation period of 14 to 16 months before giving birth to a single calf. According to the Norwegian Polar Institute, calves drink their mother’s milk for several years, but also begin to eat solid foods, such as squid, in the first 12 months of life.
Female sperm whales reach sexual maturity between 8 and 11 years old. Males can reach sexual maturity around the age of 10, but they don’t achieve a high enough social position to mate until they are 20, according to ADW. Scientists don’t know the exact lifespan of sperm whales, but evidence suggests whales can live up to 70 years, according to the Norwegian Polar Institute.
Sperm whales sleep for about 10 to 15 minutes at a time by diving into the water, turning around and napping in an upright position with their tail down, as they slowly rise to the surface, Live Science previously reported. They only spend about 7% of their time in this inactive state, which is less time than any other mammal spends sleeping, according to a 2008 study published in the journal Current Biology, which was the first study to document. this unusual sleeping behavior.
Related: Sperm whales speak with accents
What do sperm whales eat?
Sperm whales can dive up to 3 kilometers below the surface and hold their breath for two hours while searching for prey, according to the WDC. They mainly eat squid, octopus, sharks, and other animals that live in the depths of the ocean, especially giant squid. These massive invertebrates will fight predatory whales and leave scars on the whales after cutting them with the spiny, round suckers on their tentacles, according to the American Museum of Natural History.
Related: Sperm whale stranded in Australia shows scars from scuffle with giant squid
Sperm whales do not generally pose a danger to humans, but there are historical accounts and tales of whales attacking whaling ships. The whale in Herman Melville’s 1851 novel “Moby Dick” was named after an aggressive, real-life sperm whale called Mocha Dick, an albino male first seen near the Chilean island of Mocha in South America. The white whale is said to have attacked whalers and killed men, before whalers successfully hunted and killed it in 1838, according to BBC News.
Albinism is rare in nature but has been documented in many species, including whales. Individual white whales are occasionally seen today. For example, an albino gray whale (Eschrichtius robustus) was filmed off the coast of Mexico in 2019, Live Science previously reported. There have been no recent sightings of albino sperm whales, but they may exist.
Are sperm whales in danger?
IUCN considers sperm whales to be vulnerable to extinction, but after a 2008 assessment, experts are uncertain whether the sperm whale population is increasing, decreasing or stabilizing. Scientists roughly estimate that there were around 1.1 million individuals in 1700 and that the population dropped by about 67% to 360,000 individuals in the 1990s, due to whaling. Large-scale commercial whaling ceased around 1980, but it is not clear whether sperm whale populations have increased or declined further since. Japan is currently the only country still hunting sperm whales, according to ZSL.
Sperm whales face other human-made threats, such as entanglement in fishing gear, collisions with vessels and pollution, according to the IUCN. Whales are listed as endangered species in the United States and protected under the Marine Mammal Protection Act, according to NOAA.
Related: 220 pounds A “litter ball” found in the belly of a dead sperm whale
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