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Sperm whales or cachalots Physeter macrocephalus are world’s largest toothed mammals, and they have the largest brains of any living things. They belong to the cetacean group of mammals along with dolphins and whales.

Sperm whales get their name from spermaceti, secreted by the spermaceti organ. Spermaceti is an oily substance that fills up a large cavity in their heads. People called the oil spermaceti because they wrongly thought it was semen.

For a large chunk of time between the 17th and 20th century, people hunted these whales extensively to extract three things; blubber, spermaceti, and the mere chance of finding ambergris. Blubber is common to all whales and was the main source of fuel for lamps because it burned without an odor.

It was only after the discovery of kerosene that there was a decline in whaling. However, it took until 1986 before the international whaling commission (IWC) banned commercial whaling.

Beauty and fragrance

Sperm whales are the exclusive source of spermaceti and ambergris. Whalers could get up to 500 gallons of spermaceti from a full-grown whale.

The oil was useful in the production of ointments, cosmetic creams, fine wax candles, pomades, textile finishing, and later for industrial lubricants.

Today jojoba oil has replaced spermaceti in many applications so there’s even less motivation for people to hunt cachalots.

Scientists theorize that spermaceti, much like blubber might help whales with buoyancy. Another theory is that it helps with echolocation.

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Valuable excrement

Not every sperm whale has ambergris so whalers counted it as a welcome bonus if they found it in their catch. This slurry excrement is a valuable ingredient of high-end perfumes.

Some scientists believe that whales produce this greasy fluid to remove hard substances like squid beaks from their stomachs.

When excreted, ambergris can float and solidify into rock-like masses. People stumble upon it on beaches occasionally. Finding ambergris can be like winning a lottery, like a boy who found a mass that was estimated to have a value of over $60,000.

Types of clicking sounds

Cachalots also use sound to communicate. Their clicks come in four types, first is the usual loud click that can reach 236 decibels.

For reference, 150 decibels are enough to rupture human eardrums. An ambulance siren is about 120dB, and an alarm clock is about 80dB.

There was a case where the loud click paralyzed the hand of a diver for four hours. Why didn’t the sound rupture his ear?

Well, humans can’t hear all loud sounds. It has something to do with frequencies, sperm whale clicks range around 10 to 15 Hertz. Human ears can sense sound traveling at between 20 and 20000 hertz.

The limited sounds that humans can detect from sperm whales usually peak at a volume of 15 decibels. So, divers can often swim near these monstrous creatures without fear.

Also, the whales can tell that divers are not are a threat and will go on with their business or circle the strange visitor in their habitat curiously.

Other types of sounds include coda, creaks, and slow clicks. Some scientists strongly suspect that coda is sperm whale dialect unique to each individual. The patterns of sound also show variation among larger family units you can call clans. Studies show that whales can remember and identify their family members for many years

A dead sperm whale shown for scale.
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Diet

Sperm whales have teeth in their lower jaws and are carnivorous. So how do they catch food? They suck in their prey, and giant squid is a favorite on their menu.

This meal seems to come at some cost too, many sperm whales carry scars from fighting squid. Giant squids are ferocious fighters and it has puzzled scientists how sperm whales subdue such large and able prey.

Researchers have recorded the whales twisting in the water in a rapid upside-down turn when hunting to create a powerful suction that can draw in the prey from three feet away.

With several types of fish and cephalopods like giant squids, cuttlefish, and octopuses high on their menu, sperm whales needed a better way to hunt than just using vision.

Cephalopods have evolved some most sophisticated techniques of disguise and evasion.

But they can’t hide from sound.

Echolocation

Sperm whales use sound to locate prey. They make clicking noises then listen to how sound travels and bounces off objects in the water.

They can dive to dark, crushing depths 10,000 feet below sea level because of adaptations like their flexible ribs that collapse under high water pressure to prevent injury.

Echolocation helps them navigate seamounts, rock formations, and canyons in these dark waters.

Sly kleptomaniac whales

Black cod is one of the more valuable fish caught off the coast of Alaska, and sperm whales love them too. With the largest brains in the world, the whales figured a way to get easy food by stripping black cod off fishing lines.

The whales have become a serious threat to the black cod fishing industry, stealing a quarter of the catch per line on average. Some estimates show that these sly cetaceans could have cost the fishing industry upwards of 100 million dollars yearly.

People thought playing sounds would confuse the whales’ ability to find fishing lines.

They were wrong.

The sounds became dinner bells inviting the whales for quick cod snacks. Sperm whales can eat up to a third of their body weight daily.

And that is a lot of food--they weigh 35 to 57 tons, with adult males being significantly bigger and heavier than females. Sperm whales live up to 70 years old and grow as long as 12 meters. Scientists are experimenting with diversionary gongs, and this is showing early promise.

Imagine swimming in the ocean and encountering this.
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This photo is courtesy of James Nestor, author of Deep. ©2019, All Rights Reserved.

Social beings

Female sperm whales live in social groups sometimes referred to as pods with 15 to 20 whales. Males tend to live in loose groupings or pairs. The social unit of females is closer knit and raises its young and defends itself against predators together.

Scientists have observed one mother suckling two calves, and they have no evidence that these whales bear twins. They suspect this is a case of allosucking, where calves suckle different females rather than sticking with their mothers.

Since these whales breathe through the nostrils at the top of their heads, they need to surface from time to time. Foraging dives usually take between 30 to 45 minutes though some adults can go up to 138 minutes without surfacing. They then stay on the surface for around 8 minutes between dives to breathe and rest.

Sperm whales in pods usually sleep in an upright position just under the water surface. They sleep between 10 to 15 minutes, making them among the least sleep-dependent animals on earth.

Reproduction

During mating season, males join up with pods then stay for a few hours mating. After that, they leave to find another pod or forage.

Some males have been observed fighting over a pod. However, this is a rare behavior.

Flamboyant whales

Whales often breach or leap into the air, a beautiful spectacle. Scientists are not sure why they suppose it could have something to do with communication.

Some benefits of breaching can include shedding off old skin and parasites. One whale was observed breaching to get rid of some netting that had caught on its pectoral fin.

Another flamboyant display is lobtailing where they slam flukes into the water to create big splashes. Most instances of lobtailing occur when members of pods are socializing (as far as we know).

Threats

The main threats to sperm whales have been humans. Orcas also hunt sperm whales on a few occasions. The big size, strength, and overall intelligence of cachalots is a deterrent for these apex predators so they’ll often attack whenever they can’t find easier prey.

Modern threats to sperm whales include human activities such as deep-sea oil and gas exploration and mining.

Conclusion

Because these animals can dive to such deep depths, studying them is challenging. But more and more scientists are taking an interest in them, and perhaps soon we will begin to decipher their means of communication, which appears to be quite sophisticated.

References

http://www.bbc.com/earth/story/20160120-the-whales-that-speak-in-code

https://www.theguardian.com/environment/gallery/2017/mar/29/sex-death-sperm-whales-orcas-indian-ocean-in-pictures

https://books.google.co.ke/books?id=sq5C8d1hzPgC&pg=PA325&lpg=PA325&dq=sperm+whale+intelligence&source=bl&ots=tIRAAoK9zd&sig=ACfU3U1khPJt4W70XOvmS6tzrePV_i45JQ&hl=en&sa=X&ved=2ahUKEwjhpI_ivvngAhVBiRoKHfcdBFk4FBDoATADegQIBxAB#v=onepage&q=sperm whale intelligence&f=false

http://mysite.du.edu/~ttyler/ploughboy/bealeold.htm

https://everwideningcircles.com/2018/10/28/sperm-whales-clicks-go-right-through-us/

https://www.mrjamesnestor.com/#/deep/

http://www.thespermwhaleproject.org/research#ongoing-research

https://www.fisheries.noaa.gov/species/sperm-whale

https://phys.org/news/2017-09-sperm-whales-dine.html

https://www.abc.net.au/news/2018-04-09/sperm-whale-recordings-australian-antarctic-division-study/9633474

https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0201221

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Author Profile: David Kimutai

David loves visiting the ocean, and his favorite saltwater aquarium fish is the dwarf angel, genus Centropyge in the family, Pomacanthidae. He is a freelance science writer and digital marketer living in Nairobi, Kenya.

His love for aquariums started when he was young, when together with his brothers, they fished a trout from a local stream and kept it alive at home for days before releasing it.

His forum name is Davidangelfish.