Sperm Whale – Physeter macrocephalus

Sperm Whale by Linda Cox

Conservation Status: Vulnerable
Length: New-born calves 4 metre, Adult Females 12 metres, Adult Males 17 metres.
Weight: Birth weight is about 1 ton. Adults weigh up to 40 tons.


Sperm Whale dives off Kaikoura NZ

On average, females breed every 5 years. Gestation lasts between 15 to 16 months. Birth weight is about 1 ton. The female suckles it’s calve for at least 2 years, but sometimes much longer. Calves have been known to suckle from other cows within their family group.

Female Sperm whales become sexually mature around nine years. Males also reach sexual maturity (i.e. are able to produce sperm) at around 9 years, but do not breed until their late twenties. Males reach full size at 35 years of age and live to over 70 years.

Squid, occasionally including giant squid, mid water and bottom dwelling fish (Groper, Tuna, Orange Roughy and Sharks).

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. They do eat giant squid, but this is very rare.


Sperm Whale on the surface off Kaikoura NZ

Deep Diving and Sonar Hunting
Sperm whales are famed for their deep dives to the mid ocean to hunt 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 at the ocean surface and only return to the surface because of their need to breathe.

Sperm whales have been known to dive to more than three kilometers 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 sonar.

The sperm whales blowhole is at the left tip of its head. Underneath it is a structure called the “museau de singe” (monkey’s muzzle). 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 and is reflected off an air sac which sits against the whale’s skull. The sound 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 reaching, 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.


Sperm Whale raises its head off Kaikoura NZ

Spermaceti Oil
Inside the Sperm whales massive head the Spermaceti organ which 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.

Spermaceti oil congeals into a wax at 45°c and melts at 50°c. It is white and translucent, devoid of taste and smell. It was highly prized for use in cosmetics, leatherwork, as a pharmaceutical excipient and as lubricants. 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 western society to evolve as rapidly as it has.


Sperm Whale on the surface off Kaikoura NZ

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.


Sperm Whale on the surface off Kaikoura NZ

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.


Sperm Whale dives off Kaikoura NZ

If you ask a child to draw a whale they will more than likely draw the distinct shape of a sperm whale so imprinted it is upon the human psyche.

The sperm whale’s very distinct shape comes from its large block shaped head which can be anywhere from one quarter to one third of its body length. The whale’s blow hole is S shaped, very near the front of the head and shifted to the left. Sperm whales blows are distinct as they are bushy in shape, angled to the left and forward.

Sperm whales are sometimes described as a shriveled torpedo because the skin surface on the body has a distinct wrinkly appearance like that of a prune skin. Sperm whales have a ‘hump’ on their backs that is often mistaken for a fin but is actually the largest of a series of ridges.

Its tail flukes are triangular in shape and very thick. When commencing a deep dive the whale will often lift its tail high in the air.


Sperm Whale on the surface off Kaikoura NZ

Field ID

  • 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

Sperm Whale dives off Kaikoura NZ

The basic social unit is the nursery group, which comprises up to a dozen or so females and their calves. These females stay together for decades. Males leave the nursery group when they reach puberty, joining loose aggregations of other males (called bachelor pods). Very large males are solitary for most of the year, migrating to the ice edge in summer. In winter, the breeding season, they travel to warm waters search for nursery groups. On finding one, the male stays only hours or days, mates with any females in season, then leaves to search for another nursery group.

Each nursery group appears to have a matriarch. If the young of the pod are threatened in any way the adult females will surround the young with their tails facing outwards. Tragically whalers took advantage of these strong family bonds by harpooning the calves first as the adults would come to the aid of the injured animal.


Sperm Whale on the surface off Kaikoura NZ

Sperm whales are found in all the Earth’s oceans from the high latitudes to the tropics, because of this they are known as one of the earth most cosmopolitan of species. They prefer ice free waters over 1,000 meters in depth.

My great thanks to Associate Professor Steve Dawson PhD
Deputy Head of Department – Dept of Marine Science
University of Otago, New Zealand
for his generous advice and guidance in creating this page.
Marine Mammal Research Group

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


Sperm Whale dives off Kaikoura NZ