Sperm Whales

Most everything about the Sperm Whale is epic! Largest of the toothed whales, largest predator and biggest brain of any animal on Earth.

They are almost mythical creatures that are both feared and revered in many cultures around the world due to their long and involved relationship with us. So much so that if you asked a child to draw a whale they’ll more often than not draw the shape of a Sperm Whale so imprinted it is upon the human psyche.

Common Name: Sperm Whale
Other Names: Leviathan, Pot Whale, Spermacet Whale, Cachalot (French)
Scientific Name: Physeter macrocephalus
Conservation Status: Vulnerable/Endangered
Length: New-born calf 4 metres, Adult Females 11 metres, Adult Males 16 metres.
Weight: Birth weight is about 1 tonnes. Adult Females 15 tonnes, Adult Males 45 tonnes.
Gestation: 14.5–16.5 months
Weaning Age: up to 18 months
Calving Interval: 4 to 6 years 
Physical Maturity Age: Females 30 years, Males 50 years
Sexual Maturity Age: Females 7–13 years old and 8.3 to 9.2 metres in length
Males 18–21 years and 11.0–12.0 metres in length
Lifespan: 60+ years
Mating Season: July to March, peaking in September and December
Calving Season: November and March
Cruising Speed: 5 to 15km/h
Protected Since:

Field Identification
– Dark grey/brown in colour
– Distinct block shaped head
– Bushy shaped blow forward and angled to the left from a single S shaped blow hole on the left side of the head
– Triangular hump two thirds of the way along their backs
– Tail fluke thick and triangular in shape

Taxonomy
The Sperm Whale is the largest of the toothed whales. It is the only living member of the genus Physeter and one of three surviving species in the sperm whale family, along with the Pygmy Sperm Whale and Dwarf Sperm Whale of the genus Kogia.

Sperm whales name comes from the Spermaceti oil which is the oily semi liquid waxy substance found in their Spermaceti organ within their heads. The Spermaceti organ was originally thought to be the whales sex organ and the oil its semen until it was learnt that it was the whales echolocation organ. In the ancient world they were known as the “cachalot” from the very old Spanish or Portuguese cachalote via French to the English word for “tooth” or “big teeth”. The scientific genus name Physeter comes from the Greek physētēr (φυσητήρ), meaning “blowhole” (of a whale). The specific name macrocephalus is Latinized from the Greek makrokephalos (μακροκέφαλος, meaning “big-headed”), from makros (μακρός, “large”) + kephalē (κεφαλή, “head”).

Description
The Sperm Whales is the largest of the toothed whales (odontocetes), similar in size to Humpbacks and Southern Right baleen whales. Of all the whales Sperm Whales are the most sexually dimorphic as the males are much larger than the females. Fully grown females grow to 11 metres in length and up to 15 tonnes in weight, old bull males reach 16 metres in length and up to 45 tonnes. 

Sperm whales have extremely large heads making up about one third of their body length. Their single blow is unusually asymmetrically situated at the tip of their head on the left hand side, so their blow is forward and to the left at a 45º angle. They have the largest brain of any animal.

The lower jaw is long, narrow and underslung with between 20–26 large conical teeth that are up to 20 cm long and can be up to a kilogram in weight. These large teeth that fit into sockets in the upper jaw. Teeth in the upper jaw rarely erupt so are often considered vestigial. While the teeth are functional it appears that they may not be necessary for feeding as prey is swallowed whole rather than being chewed into small pieces. Healthy toothless Sperm Whales have been observed.

Sperm Whales are mostly dark grey overall. The interior of the mouth is often bright white. Some whales also have white patches on the belly. 

Sperm Whales body shape have been described as shrivelled torpedoes. Beautifully streamlined in an odd sort of way their bodies can be divided into thirds, the massive head back to the peck fin, the peck fin to the knuckle and knuckle back to the tail. The head appears smooth but the rest of the body has a corrugated almost shrivelled appearance from the peck fins to the tail. The massive huge block shaped head with asymmetrical blow hole at the left tip, long narrow underslung jaw and eyes. The peck fins are small, paddle shaped and can be pressed against the whales sides to streamlined them when they dive. In place of a dorsal fin, it has a hump (known as the knuckle) and a series of bumps (crenulations) running along the dorsal ridge to the tail. The tail flukes are very triangular in shape with a nearly straight trailing edge, rounded tips, and a deep notch. Sperm Whales don’t dive they sound, dropping their head to near vertical and raising their tail clear of the water as they go down. 

Deep Diving and Echolocation
Sperm whales are famed for their deep dives to the ocean depths to do battle with Giant Squid and other deep sea animals. It could be said that Sperm whales are more perfectly adapted to hunt and live at great depth than to be at the ocean surface and they only return to the surface because of their need to breathe air.

Sperm whales have been known to dive to well over two kilometres and for over an hour and a half in the search for food. Average dives are between 300 and 800 metres and about 45 minutes in length. To achieve these staggering deep dives and the vast changes in pressure, the whale’s body has evolved special features such as a flexible rib cage that allows the lungs to collapse – shunting air into the nasal passages where nitrogen cannot be absorbed. This helps avoids the bends. They also dramatically slow the heart rate to conserve oxygen, and withdraw the blood away from the extremities to the vital organs. Their blood has a very high red cell count, but more importantly the muscles are very rich in myoglobin, which stores oxygen. This allows a larger oxygen store than any land animal.

Although very well adapted to deep diving the bones of older Sperm whales have shown signs of pitting similar to that of a human suffering from bone necrosis, a disease suffered by human “saturation” divers. This indicates that the diving feats are close to the physiological limits.

The Sperm whale’s head is massive, at around one third of their body length. This large head contains the nature’s most powerful sonar system as well as the largest brain of any animal that has ever lived (~10kg). To hunt and navigate at these great depths in complete darkness a Sperm whale uses echolocation.

The Spermaceti Organ
Echolocation – Toothed whales have evolved the remarkable ability to use sound to hunt and navigate called echolocation. It could be said that the whales are able to ‘see’ the world ahead of them with sound. The Spermaceti Organ is found on the heads of the Physeteroidea family of whales – the Sperm Whale, Pygmy Sperm Whale and Dwarf Sperm Whale.

The sperm whales blowhole is at the left tip of its head. Underneath the blowhole is a structure called the “museau de singe” (monkey’s muzzle or lips). In this is a pair of phonic lips, which are used to make clicks. This click sound travels backwards through the nose via the Spermaceti Organ which is a shaped like an elongated barrel and sits on top of the whale’s melon at the front of its head. The clicks are reflected off an air sac which sits against the whale’s skull and then travels down and forward into the Junk bodies which have a lens like structure and out the front of the nose. Other sound reflections back and forth inside the whale’s head create a multi pulse click. The whole click is around 10-15 milliseconds long, and contains a broad range of frequencies, from about 1-40 khZ, but strongest between 2-8 kHz. They are the loudest sounds in the animal kingdom, each click may reach the sound level of a rocket launching pad. The lower jaw is used as the primary reception path for the returning echoes as it contains fat filled canals that transmits sound to the inner ear.

Scientists have been able to estimate the size of whale’s Spermaceti Organ by measuring the time intervals between the clicks and reflections and this then gives a good indication of the overall size of the whale.

When the whale is swimming normally they generally emitted low frequency sounds and the echoes provide the whale with information about the ocean around them such as the waters depth, seafloor, obstacles and any other animals near them. Echolocation is extremely sensitive and it is believed that it may give the whales a a three dimensional view of the world. Recently it has been proposed that the whales may be able to stun their prey by using very high intensity sounds.

Spermaceti Oil – The Spermaceti Organ is filled with Spermaceti oil which early whalers mistook for the whales sperm – hence the whale’s name. Spermaceti from the Greek sperma, seed and Latin cetus, whale. The oil congeals into a wax at 45°c and melts at 50°c. It is white and translucent, devoid of taste and smell. A large sperm whale may contain as much as 1,900 litres of this oil. It was highly prized for use in cosmetics, leatherwork, as a pharmaceutical excipient and as lubricants.

It has also been proposed that by controlling and changing the Spermaceti oils temperature and therefore its density Sperm Whales may be able to control their buoyancy, assisting them with their deep diving. This theory is still hotly debated. 

The wax was used to make high quality candles. The term Candlepower or CP was set in 1860 as a measure of luminous intensity produced from a candle made from pure Spermaceti. Today we use a Candela as a unit of luminosity which equates directly to the former Candlepower.

It should be noted that before petroleum products superseded whale oil, whale oil drove the industrial revolution and thus enabled western society to evolve as rapidly as it has.

Skeleton 
The Sperm Whales skeleton is adapted for deep diving as the rib bones are attached to the spine by flexible cartilage which allows the ribcage to collapse rather than snap under the immense pressures. Even though the whales are perfectly adapted to deep diving the bones of older animals do show signs of pitting suggesting that diving to such great depths does have long-term effects. Decompression sickness causes pitting in humans so this damage may indicate that Sperm Whales may be susceptible to decompression sickness as well. 

As an adaptation to echolocation toothed whales skulls are asymmetrical in shape. The echolocation organs sit on the forehead of the whale above the upper jaw giving the skull a distinct elongated shape. An air sack sits agains the skull and the nasal passages are skewed towards the left side of the skull. The effect of the asymmetry is that sound waves will strike the skull will be channeled to the ear differently allowing the whale to deduce the direction the sound came from. 

Teeth
The Sperm whale is the largest of the toothed whales. It has a long narrow lower jaw with large teeth that fit into sockets in the upper jaw. Teeth are cone shaped; weight up to a kilogram and are up to 20cm in length in large males. Normally there are no teeth in the upper jaw, but a few vestigial teeth may be present. While the teeth are functional the whales tend to swallow their prey whole rather than chewing them into small pieces.

Ambergris
The main food source for Sperm whales are the various Squid species which they can digest completely except for the sharp beaks. To ease their passing of these sharp objects through the intestines the whales secrets a solid waxy substance called Ambergris. The whale either passes these lumps or vomits them if they are too large.

Fresh Ambergris has a marine fecal odor, but as it ages it acquires a sweet earthy scent. It is highly prized as a fixative in perfume manufacture. Pound for pound Ambergris was once worth twice as much as gold – currently it is valued at $65usd a kilogram.

Distribution and Movement Patterns
Oceania – Sperm Whales are seen right across Oceania. The females and young males are restricted to warmer waters, generally north of approximately 45° S, while the older bull males travel to and from colder waters of the Southern Ocean right to the edge of the Antarctic pack-ice. 

Although Sperm Whales are considered to occur throughout the Southern Hemisphere is is believed that it is the males who will travel the greatest distances between oceans where as the females tend to have much smaller geographic ranges. Recent studies of the complex social structure suggest that Sperm Whales may occur in severely fragmented populations where their ‘vocal clan’ may be a more important factor in genetic structure than geography. This complex social structure may increase the potential for loss of particular subpopulations and their associated genetic diversity and social culture.

Sperm Whales are considered a deep ocean whale as they are only seen close to the coast at certain locations where water depth is in excess of 200 metres depth such as Albany (Western Australia), Kangaroo Island (South Australia) and in Kaikoura (New Zealand). 

Kaikoura – Just off the coast of Kaikoura on the east coast of New Zealand’s south island is the Kaikoura Canyon plunging to over one kilometre in depth. Here there is a semi-resident bachelor pod of Sperm Whales that gather hunt squid and fish. So well known is each individual whale that they have been named – Tutu, MatiMati, Manu, Tiaki and Saddleback. 

Global – The Sperm Whale are seen in deep waters in all oceans (and confluent seas) of the world, from the equator to the edges of the polar pack-ice. They are usually found well off shore in the mid ocean but also occasionally come close to the coast where water depths are over 200 metres, particularly in submarine canyons at the edges of the continental shelves. 

As Sperm Whales are found throughout the Earth oceans global estimates of their abundance are based upon historic whaling data and recent visual surveys covering less than 24% of their global habitat and then extrapolated out. So it is estimated that the world wide population is between 300,000 and 450,000 whales. This is thought to be just over 30% of the original pre whaling population that is estimated to have been around 1,267,000 individuals. So despite over 900 thousand Sperm Whales being killed by whaling they are still considered to be the most abundant of the large whale species. Given that commercial whaling has now been stopped it thought that the population is increasing. 

The family pods of female and juvenile Sperm Whales remain in the warmer tropical waters nearer the equator and do not undertake migrations. The male whales move further and further away from the equator towards the poles as they grow and age. So you find the oldest and largest bull males near the edge of the Antarctic pack-ice only occasionally returning to the warm water breeding area to seek out the females. 

Habitat
Sperm Whales are cosmopolitan by nature and are found in all the worlds oceans. They are thought of as a deep ocean animals as they tend to be found in offshore areas with a water depth greater than 600 metres. They are seldom found in waters less than 300 metres deep. The females are found in warmer waters of the low latitudes (less than 40°N/S) and in deep water generally over 1000 metres. These conditions generally correspond to sea surface temperatures above 15 °C. Female Sperm Whales are sometimes seen near mid ocean islands. Sperm Whales are also known to gather in areas where the seabed rises steeply from great depths causing upwelling and concentrations of their prey.

Males will stay within their family pod until they reach puberty (anywhere between ages 4 and 21 years of age) when they will separate away and start migrating towards the poles. They may join all male ’bachelor’ such as the one found at Kaikoura. The oldest and largest bull males live solitary lives generally south of about 45° S right down to the edge of the Antarctic pack ice. Occasionally the males will return to the low latitudes to rejoin with the females for breeding. 

Sperm Whales occur around Australia’s subantarctic islands, such as Macquarie and Heard Island, feeding on deep water species.

Behaviours
Sperm whales are famed for their dives to the ocean depths and epic battles with Giant Squid. They really are champion divers better adapted for being at great depth that at the oceans surface. 

Sperm whales bodies have adapted to allow them to dive to thousands of metres in depth and using their ability to echolocate hunt for prey. These dives can be greater than 1,000 metres in depth and last for up to two hours. To do this the whales must recharge their blood with lots of oxygen so they are often seen just laying on the surface like a giant log or having a nap between dives. Once they are ready to dive again they will sound going almost vertically strait down and lifting their tails clear of the water. 

The basic social unit of Sperm Whales is the nursery group. These are highly stable social groups based around related females and their offspring that is ruled by a matriarch. These females stay together for decades. These nursery pods of females live in the open ocean in the warmer lower latitudes. Males will occasionally visit these pods to mate but are normally solitary. Calves are born after a 14-16 month gestation and will stay with their mother for many years. Calfs will be eating solid food by the time they are one but may continue suckling for several more years until the next calf is born. Male calves will leave their family pod anytime between 4 and 21 year of age. Females will remain with their family pod caring for the younger calves. Sperm Whales like Killer Whales are the only mammal species other than humans, in which females continue to live and play a role in family/social groups after they have stopped breeding.

Female and young male sperm whales are social and sometimes can be seen in pods of up to 50 whales. The females are fiercely protective of one another and particularly of the calfs. If threatened the whales will gather around the most venerable, sick or injured member of the pod forming whats called a “marguerite formation” where the whales positioning themselves in a circle on the surface like the spokes of a wagon wheel, with their heads pointing towards the centre and their tails on the outside ready to defend the pod. The nursery pods spend around three-quarters of their time foraging and hunting and a quarter of their time socialising. When socialising they will spend much of the time rubbing against each other. 

Males leave the nursery group when they reach puberty, joining loose aggregations of other males of similar age (called bachelor pods). Very large males are solitary for most of the year, migrating to the ice edge in summer. In winter, during the breeding season, they will travel to warm waters in search for nursery groups. On finding one, the male will only stay for a few only hours or days, mates with any females in season, then leaves in search for another nursery group.

Sperm Whales emit complex patterns of clicks called codas. It would appear that each whale has its own distinct coda and scientists think that whales can recognise one another by their individual codas. 

Sperm Whales can engage in aerial behaviours including breaching and lobtailing but normally they aren’t the most exciting whale to watch on the surface just laying their like a giant log as they recharge their system with fresh oxygen or sleep. 

Sadly Sperm Whales are one of the species known to strand in large groups. Why they do this is still not understood but some theories include illness within the leader, becoming disorientated around areas where the seabed gently slopes into shallow water or even by being effected by magnetic anomalies.

Feeding
On Sperm Whales long dives into the oceans depths they actively hunt a large variety of prey including squid, octopuses, mid water and bottom dwelling fish (Groper, Tuna, Orange Roughy and Sharks), rays and sharks. Although they are famed for battling with Giant or Colossal Squid these encounters are probably quite rare, as most of the squid eaten by Sperm Whales are relatively small. Off Kaikoura New Zealand, they mostly eat Warty Squid, which are not targeted by fisheries. Warty squid are about usually around 1m long, weighing 2-3 kg. Sperm Whales seem to forage mainly on or near the ocean bottom, often ingesting stones, sand, sponges, and other non-food items. Sperm Whales feed regularly throughout the year on average consuming about 3.0–3.5% of their body weight per day.

How Sperm Whales hunt is still a bit of a mystery as they do so in the darkness at great depth. Several theories on how they hunt have been proposed including: Using echolocation to find their for prey as other toothed whales do. Seeing the squids bioluminescence in the dark. It has even been proposed that as the whales eat so much squid they may absorb this bioluminescence and their white lips my glow to attract prey into the open mouths. They may also randomly searching for prey by swimming with their mouths open, this was suggested after Sperm Whales were found entangled in deep sea cables. They have also been known to co-ordinate their foraging dives, and they sometimes forage in a rank, often over 500 m long, with whales spread out underwater. And much to the annoyance of the fisherman Sperm Whales have been known to pluck fish off fishing longlines, particularly in the subantarctic, around islands such as South Georgia.

Life Cycle
Sperm Whales, like other toothed whales, are gregarious by nature often living in large pods. Matriarchal nursery groups form the basic unit of social organisation in Sperm Whales. Ruled by a grandmother, her daughters and grand daughters these family pods are very tightly bonded with individuals females remaining part of this group for their entire lives. As many as 30 mature females and their offspring may be part of a nursery group, although this group may be spread out over a very wide area in the warm arm tropical waters located towards the equator. Within this maternal nursery school females (and young males) will care for the calves including looking after the sick or injured and baby sitting when their mothers are off foraging. Male calves will remain with their birthing pod until they reach puberty, then they will leave often joining up with other males of similar age to form bachelor pods. As the males grow and age they move further and further towards the poles. Once they attain social maturity and are capable of competing for females they will leave the bachelor pods to join breeding pods made up of small numbers of animals. The oldest and largest bull males will travel seasonally to higher latitudes where better feeding grounds may be found. 

The Sperm Whales mating season (in Southern Hemisphere) extends over many months between July to March, peaking between September and December. The prime aged bulls (n their late 20s and older) will travel from their feeding ground much further south seeking out females on the tropical breeding grounds. Female have synchronised estrus cycles allowing the males to visit only briefly yet achieve maximal breeding success. So a males may spend as little as a few hours with a female pod. Calves weighing about one ton and up to 4 metres in length are born after a 15 to 16 month pregnancy in tropical and temperate waters between November and March. Females will breed on average every 5 years. Calves will begin taking solid food before they turn one and continue to suckle sporadically for as long as 13 years. Calves have been known to suckle from other females within their family group.

There are no known calving grounds in Australian waters. 

Female Sperm whales become sexually mature between 7–13 years old and 8.3 to 9.2 m in length whilst males reach sexual maturity at between 18–21 years (but probably only start breeding once they are in their late twenties) and 11.0–12.0 m in length. Males reach full size at 35 years of age. Sperm Whales can live to ages in excess of 60 years. 

Sperm Whales calves have been known to be killed by Killer Whales. Adult whales have been observed being harassed by Pilot Whales, False Killer Whales and Killer Whales. Male Sperm Whales are also known to fight one another. 

Little is known about diseases affecting the natural mortality rate of Sperm Whales. The bones of older whales show signs of ‘pitting’ which may indicate that they suffer decompression sickness (what is called the bends in humans).

Threats
Tragically Sperm Whales were one of the most sort after commercial whaling species and overfishing cause significant declines in the world wide population. Commercial whaling did not finish in Australia (Albany, Western Australia) until 1978. 

Current threats to Sperm Whales primarily include: shipping collision as the commercial shipping lanes are beyond the edge of the continental shelf, entanglement and pollution such as oil spills, dumping of industrial wastes and particularly plastic pollution that whales may ingest. Sperm Whales like all whales are lightly to be very sensitive to any disturbance by loud or unfamiliar noises, so mineral exploration using seismic testing and military sonar disturbance may greatly affect them. 

Sperm Whales have a low reproductive rate only breed every four to six years so any population recovery is likely to be a very slow process.

My great thanks to Professor Steve Dawson PhD
Head of Department – Dept of Marine Science University of Otago, New Zealand for his generous advice and guidance in creating this page.
New Zealand Whale and Dolphin Trust

I would also like to thank Lisa Bond Marketing and Communications Officer Whale Watch Kaikoura for all her support, advise and encouragement in creating this page.
Whale Watch Kaikoura

References/Sources
Australian Department of the Environment, Canberra
NSW Department of the Environment
NZ Department of the Environment
International Whaling Commission
Whale Watch Kaikoura
NOAA Fisheries
Whales, Dolphins and Porpoises by Mark Carwardine
Whales, Dolphins & Seals: A Field Guide to the Marine Mammals of the World by Hadoram Shirihai and Brett Jarrett