SPERM WHALE BEHAVIOR
Giant sperm whales are migratory (make seasonal movements between regions, such as between breeding and wintering grounds), social (associates with others of its species; forms social groups), and have dominance hierarchies (ranking systems or pecking orders among members of a long-term social group, where dominance status affects access to resources or mates). [Source: Liz Ballenger, Animal Diversity Web (ADW)/=]
Daniel Stone wrote in National Geographic: “Sperm whales are majestic, intelligent, and maddeningly elusive, escaping to ocean depths when pursued or spooked....Scientists know sperm whales as the ocean’s largest toothed predators. They have the biggest brains of any known animal, can weigh up to 45 tons, and have been observed displaying humanlike qualities, such as curiosity and playfulness. But despite their size and their expressiveness, sperm whales remain one of the ocean’s biggest mysteries. Do they share complex ideas? What are the dynamics in their family groups? And what goes on in those giant brains? [Source: Daniel Stone, National Geographic, October 2018]
Sperm whale sometimes put the welfare of the group above their own lives. If the one whale is injured and incapacitated the other members of the group sometimes lift it out of the water to breath. Whalers reported many instances of whales in a group coming to the rescue of a harpooned whale by biting the harpoon line or attacking the whaling boat. Females protect their young in a circle like musk oxen.
Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se; Encyclopedia of Life eol.org; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems ; Monterey Bay Aquarium montereybayaquarium.org ; MarineBio marinebio.org/oceans/creatures
Sperm Whales Social Behavior
Sperm whales, particularly females, are very social and group themselves roughly by age and sex in group sizes of 100 or more individuals. Loose family groups of about 30 individuals, however, are more common. Female sperm whales and young hang out in matrilineal groups of 10 to 40 individuals. These are joined by bull males during the breeding season. Larger aggregations are occasionally seen. Groups are often made up of either bachelor bulls (sexually inactive males) or "nursery schools" of mature females and juveniles of both sexes. Older males are usually solitary except during the breeding season.
Males are loners who leave the groups of their mothers at age six, maturing 20 years later. Young males form loose bachelor herds, but become increasingly solitary as they age. DNA evidence showing that members of matrilineal groups are related through their fathers, suggesting that males visit the same female groups repeatedly or mate with several females. /=\
Most females form lasting bonds with other females of their family, and on average 12 females and their young will form a social unit. While females generally stay with the same unit all their lives in and around tropical waters, young males will leave when they are between 4 and 21 years old and can be found in "bachelor schools,” comprised of other males that are about the same age and size. As males get older and larger, they begin to migrate toward the poles and slowly bachelor schools become smaller; the largest males are often found alone. Large, sexually mature males that are in their late 20s or older will occasionally return to the tropical breeding areas to mate. [Source: NOAA]
Describing a group off of Mexico, Eric Wagner wrote in Smithsonian magazine: We head “toward a group of about 25 sperm whales — adult females, juveniles and suckling calves up to 2 years old. The calves and juveniles are 15 to 20 feet long, and some of the larger females are more than 30 feet from head to tail. We approach one that appears to be sleeping, its rumpled back and bulging head rolling with the waves. It snorts awake and swims off as its companions drift away from us in loose pairs and trios. We trail after one of the pairs, a female and calf. The two idle along, nudging each other and blowing mist. Then the female surges forward. The huge muscles of her flanks go taut as she arches her back and heaves out her tail. Water cascades off her broad tail flukes, and she dives. The calf follows, Leviathan in miniature, its flukes aloft as it slides into the sea. The other whales start to dive”....We “wait the whales’ return. Five minutes turns into ten, then fifteen. Still they do not surface. [Source: Eric Wagner, Smithsonian magazine, December 2011]
Sperm Whale Pods and Clans
In 1985 sperm whale expert Hal Whitehead of Dalhousie University found that the typical pod of sperm whales numbered between 3 and 20 or so individuals and was comprised almost exclusively interrelated adult females and immature whales. Adult males made up only 2 percent of the whales he observed. Nathaniel Philbrick wrote in Smithsonian magazine: “ The females work cooperatively in taking care of their young. The calves are passed from whale to whale so that an adult is always standing guard when the mother is feeding on squid thousands of feet below the ocean’s surface. As an older whale raises its flukes at the beginning of a long dive, the calf will swim to another nearby adult. [Source: Nathaniel Philbrick, Smithsonian magazine, December 2015]
Sperm whales travel in these lifelong, female-led social pods. “Young males depart the family unit at around 6 years of age and make their way to the cooler waters of the high latitudes. Here they live singly or with other males, not returning to the warm waters of their birth until their late 20s. Even then, a male’s return is fairly transient; he spends only eight or so hours with any particular group, sometimes mating but never establishing strong attachments, before returning to the high latitudes.
Sperm whale families belong clans that’s culturally distinct from other clans. Each clan communicates in its own dialect of click patterns that have been compared to Morse code. The pioneering studies that worked a lot of this out were done by Whitehead who tracked sperm whale social around the Galápagos Islands and other places. Since 2005, Shane Gero, a professor at Denmark’s Aarhus University has come to Dominica in the Caribbean Sea to study sperm whales groups. Craig Welch wrote in National Geographic: Rather than finding a “monomaniac incarnation” of “malicious agencies” as Herman Melville described the sperm whale in Moby-Dick, Gero sees peaceful, playful animals. He can identify dozens on sight. There’s Canopener, who toys with researchers, pulling close to their vessel before rolling sideways to eyeball Gero’s crew... The one with the serrated fluke is called Knife; the one with the weird scoop in his was Spoon. [Source: Craig Welch, National Geographic, April 15, 2021]
The whales he knows are local “island specialists,” Gero tells me. He follows them as they move through underwater canyons off Dominica, between the islands of Guadeloupe and Martinique. He has tracked them sleeping, giving birth, nursing, making their first dives, playing with cousins, dying. He’s recorded them swimming deeper than most submarines travel. He knows their lives so intimately his kids at home can recite their names.
But today, after more than a week at sea, we woke to find the locals gone, replaced by the eight outsiders riding swells around us....These new whales are animals he barely knows, itinerant vagabonds from a second whale community. They occasionally share space with the regulars, but never interact with them...To Gero, they are unmistakable evidence that Dominica is home to parallel whale traditions — two cultures as divergent as farmers and nomadic hunter-gatherers.
Sperm Whale Feeding
Sperm whales hunt for food during deep dives that routinely reach depths of 610 meters (2,000 feet) and can last for 45 minutes. They are capable of diving to depths of over 3,500 meters (10,000 feet) for over 60 minutes. After long, deep dives, individuals come to the surface to breathe and recover for approximately nine minutes. Because sperm whales spend most of their time in deep waters, their diet consists of many larger species that also occupy deep ocean waters. Sperm whales can consume about 3 to 3.5 percent of their body weight per day. [Source: NOAA]
Sperm whales feed on everything from tiny lantern fish to giant squid and consume creatures near the surface and deep in the ocean. They feed primarily on squid and and deepwater fishes, but also take sharks and skates. Usually they swallow their food whole. By one estimate sperm whales eat as much squid in terms of weight as half the human population of the world. Some scientists believe that sperm whales hunt by sending out sounds that are so loud they stun their prey enough to temporarily incapacitate them so a whale can easily gobble them up.
A single sperm whale can eat more than one ton of squid per day. In the Sea of Cortez, between Mexico and Baja California, the main prey of sperm whales is jumbo squid (Dosidicus gigas): Sperm whale expert Kelly Benoit-Bird of Oregon State University told Smithsonian magazine: “In the Sea of Cortez, you know that what sperm whales do is driven by what the squid do. So you expand. You ask: What is driving the squid?” It turns they are often pursuing lanternfish which in turn are go after zooplankton.
On Benoit-Bird’s sperm whale feeding data, Eric Wagner wrote in Smithsonian magazine: The acoustic reading shows a ten-minute window, with time on the horizontal axis and depth on the vertical. One thick band stretches from 700 feet or so to more than 900 feet. This is the deep scattering layer, the zooplankton and lanternfish. Individual squid, one visible as a blue-green smear, the other in orange, are among them, perhaps feeding. A school of squid shows up a few minutes later, loitering about 60 feet from the surface.
The real drama, though, starts at one minute and 55 seconds, with a pair of red and orange squiggles: two sperm whales, one near the surface and the other more than 300 feet under the boat. The latter dives to a school of squid nearly 400 feet deep. The tracks of the squid and the whale converge, are lost as they move into the band of fish, and pop out of the jumble...We can imagine the wan glow from a school of lanternfish, the jumbo squid among them, and a sperm whale moving through the gloom with relentless purpose. The whale searches with usual clicks and gives a quick creeeeeek! as it locks onto the squid. There is a rush of pressure from its head wave as it surges to its prey, jaw agape, and the jet from the squid as, panicked, it bursts away into the darkness.
Sperm Whales and Giant Squids
According to some estimates a 50-ton sperm whale may eat up to three or four giant squids a day (the stomachs of some dissected sperm whales contains handfuls of giant squid beaks). Whalers that hunted sperm whales until the 1980s reported harpooned sperm whales vomiting up giant squids with tentacles as thick as a man's thigh.
Giant squids are relatively slow, which makes them easy prey for sperm whales, but they are believed to put a some degree of fight. Sperm whales almost always have scars from the squid's sharp toothed suckers around their mouths. Some of the sucker scars are 13 centimeters across. Beaks larger than those of the largest specimens have been found in sperm whale stomachs.
Describing an imagined battle between a bull whale and female giant squid, Stanford University professor Stephen Palumbi wrote in “Extreme Life of the Sea”:“40 tons of flesh and hot blood collide at 10 feet per second...She rolls with the blow, wrapping her arms around the attackers head and jaws. Hooks tear long gaping wounds in his skin, layering fresh damage on top of chalky white scars. He’s no stranger to this kind of fight.”
Eric Wagner wrote in Smithsonian magazine: The most celebrated natural antagonism between sperm whales and squid, conjuring up images of the Leviathan grappling with the Kraken in the abyssal trenches, almost certainly involves the giant squid, a species that grows to 65 feet long and closely resembles the creature described in Moby-Dick. In the novel’s “Squid” chapter, Starbuck, the first mate, is so discomfited by a squid that floats up in front of the Pequod — “a vast pulpy mass, furlongs in length and breadth, of a glancing cream-color, lay floating on the water, innumerable long arms radiating from its centre” — that he wishes it were Moby-Dick instead. [Source: Eric Wagner, Smithsonian magazine, December 2011]
The nonfictional relationship between sperm whales and squid is pretty dramatic also. hey do eat giant squid on occasion, but most of what sperm whales pursue is relatively small and overmatched. With their clicks, sperm whales can detect a squid less than a foot long more than a mile away, and schools of squid from even farther away. But the way that sperm whales find squid was until recently a puzzle.
Sperm Whale Reproduction
Sperm whales are viviparous, meaning they give birth to live young that developed in the body of the mother, and engage in seasonal breeding. Females give birth every five to seven years. The peak of the mating season is in the spring in both Northern and Southern hemispheres. The average number of offspring is one. The gestation period is 14 to 16 months. The average weaning age is 24 months. Females reach sexual maturity between 8 and 11 years. The average age at sexual maturity for males is 10 years. Males have a two-meter retractable penis. Some of suggested that this may be the source of whale’s common name. [Source: Liz Ballenger, Animal Diversity Web (ADW)]
Female sperm whales reach sexual maturity around nine years of age when they are roughly nine meters (29 feet) long. At this point, growth slows and they start producing calves. Unlike females, puberty in males is prolonged, and may last between ages 10 to 20 years old. Even though males are sexually mature at this time, they often do not actively participate in breeding until their late twenties, perhaps because they do not have a high enough social status in a breeding school until that point or only then are they able to challenge dominant males. [Source: NOAA]
Sperm whales are polygynous (males having more than one female as a mate at one time). /=\ During the breeding season, breeding schools composed of 1 to 5 large males and a mixed group of females and males of various ages form. At this point, there is intense competition among the males for females (including physical competition resulting in battle scars all over the heads of males). Only about 10 to 25 percent of fully adult males in a population are able to breed. /=\
Sperm Whale Young
Most calves are born in the fall. They are about four meters (13 feet) long at birth and weigh around 1,000 kilograms — about 1/25 the weight of females.. Although calves begin eating solid food before one year of age, they continue to nurse for several years.
Scientists had wondered how sperm whale mothers gave milk to their long-jawed young. Females have slits that contain hidden nipples. When a calf is hungry, it pushes its jaw into the slit and milk is released, allowing it to feed. Sometimes sperm whale calves suckle from females that are not their mother. Each sperm whale social unit may nurse differently. In some, aunts or grandmothers also provide milk to offspring. Or a single female may nurse two calves at once, even if neither is hers. Researcher Shane Gero observed one young sperm whale get its tail entangled in a fishing rope. It was wrapped so tightly it threatened to amputate her fluke. Unable or unwilling to dive for food, she seemed to start nursing again. Finally the whale was freed and was able to resume feeding on squid again.
Craig Welch wrote in National Geographic: One afternoon we spot a female sperm whale named Rounder. She’s floating at the surface with two calves, only one of which is hers. Baby whales don’t dive deep for squid, Gero explains, so an adult protector stays topside as the unit hunts. We’re watching Rounder babysit. [Source: Craig Welch, National Geographic, April 15, 2021]
Every unit does this differently. Some let the young slip beneath their bellies to suckle. In some units, calves get watched by nonrelatives, but get milk only from mom. In Rounder’s group, moms and grandmothers share babysitting and nursing duties, but only for calves in their bloodline. In another, one female plays wet nurse to two calves at once — even though neither is hers.
Head Battles and Sperm Whale Mating
In the winter males search for females to mate with. To successfully mate they must fend off other males. Their mating behavior is similar to that of elephants.
Males are believed to use their massive foreheads to batter rivals during battles over females. The male forehead is huge, tough, padded with tough skin and blubber. The brain is situated well back out of harm’s way. For additional shock absorption they have six vertebrae that are fused together.
The sperm whale is designed to withstand and deliver blows with its head. Head on collisions appear to result in relatively minor damage to the whales. By some estimate the spermaceti in the head is ten times better at absorbing shock than the other, blubber-covered part of the body. If a whale can use his head to deliver a blow to another part of the body the damage could be far worse. The best strategy for an attacking sperm is to strike a rival broadside or attack from below or above. The best defense is either to get out of the way or face the attacker head on.
Killer Whales Attack and Kill Sperm Whales
Describing a killer whale attack on a pod of sperm whales off the California coast, Robert Pitman and Susan Chivers wrote in Natural History magazine, "Nine sperm whales have gathered to form a “rosette,” their heads pointing to the center, their bodied radiating out like the spokes of a wheel...sperm whales for a ring with their tails out — the out — the tail of a large whale being a formidable weapon." [Source: Robert Pitman and Susan Chivers, Natural History, December 1998]
"One of the [killer whale] adults charges into the rosset, arches, and broadsides a sperm whale, hitting it hard below the waterline. The wound she inflicts must be serious because fresh blood wells up on the surface of the water...The sperm whales, however continue to hold their formation. Soon four female killer whales come charging in, this time from about a quarter mile out. At one hundred yards, they lunge high out of the water, shoulder to shoulder, in synchrony of practiced pack hunters. Circling rapidly around the rosette, they stay just beyond the reach of those dangerous tails. One cuts in and locks her jaws onto the side of the sperm whale. We can see flashes of white below the surface as she spins around, tail pumping, trying to wrest a mouthful of flesh. As fresh blood again colors the surface, two more killer whales join the attack."
"The group is charging at the sperm whales from both sides. Twisting their bodies and violently shaking their heads like huge hungry sharks, the killer whales try to wrench off mouthfuls of what must be very tough flesh. The tempo of the attack picks up" as one sperm whale is separated from the rosette. Two sperm whales leave the rosette formation and approach their isolated companion. One on each side, the two begin to herd the severely injured whale back to rosette...Eventually the sperm whales become disoriented. They try and fail to hold the rosette formation. All appear to be wounded, several severely. The number of killer whales in the area is building — we now estimate there are 40 or 50."
"The battle has reached its peak. Several sperm whales have been dragged away from the rosette and are being savagely attacked. One of the largest rolls slowly over on its side like a sinking ship and appears to be very near death. Then, as if on cue, a bull killer whale rushes in. He broadsides the isolated sperm whale, pushing it sideways through the water. Like an angry dog he seizes it by the flanks and shakes it violently from side to side, then swings its around in a wide arc. Just as abruptly as it began, this final assault ends, and a clam covers up the evidence. The bull slips away, dragging the dead sperm whale with him...Every member of the herd has been injured, and all may die from wounds received...One has been disemboweled, its intestines draped over its back...Another rolls over...hanging from it side is a huge slab of blubber, perhaps eight inches thick and as a big as a queen-size mattress. The attackers have been skinning this whale alive.”
Image Source: Wikimedia Commons, NOAA
Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.
Last Updated May 2023