Monday, September 8, 2014

10 Impressive Facts About Sperm Whales

Title Picture: Gabriel Barathieu

Guess what:  I think sperm whales are really freaking cool animals.  Here are 10 facts about them:

10: Why They’re Called Sperm Whales

The name “sperm whale” might lead to a few snickers in a lecture hall.  It refers to the spermaceti organ, which fills most of the whales’ distinctively-shaped heads, as well as the oil contained within.  There have been multiple theories on the function of this organ.  Various scientists have postulated that it is used as a battering ram, functions as a buoyancy control mechanism, or assists in the whales’ use of echolocation.  The spermaceti oil was considered a highly desirable commodity, useful for lamp oil and as a general lubricant.  It was also a very good material for making candles.  Unfortunately this led to extensive hunting of the sperm whales, as a single spermaceti organ could yield up to 1900 liters (502 gallons) of spermaceti oil.  The oil tends to thicken and turn white when coming into contact with air, leading early whalers to mistake it for the animal’s semen, thus originating the unfortunate name.

9: Two Separate Sperm Whales Inspired Moby Dick

The sperm whale commands a fierce reputation thanks to the species’ association with Herman Melville’s Moby Dick.  The novel was inspired by two separate incidents involving sperm whales.  The more well-known of the two is likely the sinking of the Essex, a whaling ship, in 1820.  On a whaling voyage in the South Pacific, a very large sperm whale, reported to be 26 meters (85 ft) long, charged and rammed the Essex.  This first impact was damaging enough that Owen Chase, the Essex’s first mate, was already anticipating that they’d lose the ship despite efforts to pump water out.  The whale wasn’t finished after the first blow, however.  He swam several hundred yards out, turned around, and rammed the ship a second time, causing more damage.  The Essex sank very quickly after the second blow.  The survivors were stranded at sea in lifeboats, eventually having to resort to cannibalism to survive, first eating the dead and then drawing lots to determine who would be killed for food.  Only five men were still alive by the time rescue came.

The second inspiration for Moby Dick was an actual albino sperm whale frequently encountered near the Chilean island of Mocha.  He was appropriately named “Mocha Dick.”  This whale was infamous for his aggressive attacks on whalers.  When he was finally killed, he measured about 21 meters (70 ft) long and had 20 harpoons, left over from various encounters with whalers, lodged in his flesh.

8: Largest Toothed Animals on Earth

Sperm whales are large animals.  They’re not the largest animals in the world, but they are the largest animals with teeth.  Males, on average, are 16-18 meters (52-59 ft) long, with females often around 25% shorter.  It is believed that extensive whaling in the past has actually shrunk the average size of adult sperm whales, (note the reported lengths of the two whales in the above entry) as big males would yield the most spermaceti oil and therefore be the most targeted.  While old reports can certainly be exaggerated, note that the Nantucket Whaling Museum has a 5.5 meter (18 ft.) jawbone that, based on typical sperm whale proportions, would have belonged to a 24 meter (80 ft.) animal.

Sperm whale teeth are impressively large themselves, measuring up to 20 centimeters (8 in) long and weighing up to one kilogram (2.2 lbs).  There are typically 25 pairs of these conical teeth along the lower jaw, with the upper jaw containing sockets to accommodate them.  Despite their crushing appearance, the teeth are not needed for feeding, and are believed to be used for aggression between males.

7: They Aid in the Study of Giant Squid (By Eating Them)

Sperm whales dive deep underwater to feed, where they have little competition for food.  They eat a variety of deep-water animals, most famously the giant squid.  Sperm whale feeding is of course difficult to observe and study given the depths at which it occurs, so to this day scientists know little about the actual process of catching giant squid.  The presence of sucker scars that could only have been made by giant squid indicate that the squid may grab onto the sperm whale’s head in an attempt to prevent being eaten.  These attempts likely often fail, as many sperm whale stomachs have been found to contain giant squid beaks and other parts within.

As giant squid themselves are notoriously hard to study given that they too live deep underwater, sperm whales’ predation of them can be an asset to squid scientists. Sperm whale stomachs have been used as a natural means of obtaining samples to learn more about giant squid.

6: Incredible Digestive Systems
If the sucker scars are any indication, sperm whales eat some rather formidable prey.  Luckily, they have an equally formidable digestive system.  Sperm whales possess four stomach chambers, the first of which has very thick and muscular walls.  This is meant as a defense against the beaks and suckers of squid which are swallowed whole.  Sucker marks found inside this chamber by whalers imply that prey may even be swallowed alive at times.  After being held in this first chamber, the prey is moved to a second, larger chamber where the bulk of the digestion takes place.  Most of the squid beaks are collected here and eventually vomited back out, though some make it into the intestines, which are the longest of any animal.

Ominously, sperm whales are technically capable of swallowing humans whole.  However stories of whalers being swallowed and found alive inside the stomachs are likely false, as there would be no way to breathe inside the digestive tract. 

5: Their Waste Can Be Valuable
As mentioned above, occasionally a squid beak makes it through the stomach chambers and into a sperm whale’s intestines.  This is theorized as the reason for the formation of a substance called ambergris, which is valued for its use in perfumes.  The beaks are believed to irritate the walls of the intestine, causing lumps of ambergris to form around the sharp beaks, protecting the intestine.  These lumps are eventually defecated, and sometimes vomited.  This is a relatively uncommon occurrence; nearly 20 years of records from a fishery in the Azores showed that ambergris was found in only one percent of sperm whale intestines.  As a result, for years many did not even know the source of ambergris, believing it to come from an unknown animal.  Also due to this rarity, ambergris can be extremely valuable.  A 14.5 kg (32 lb) chunk found by a couple in Australia in 2006 was worth nearly $300,000.

4: Largest Brains on the Planet

Many things about sperm whales are gigantic, so why not their brains?  In fact, they possess the largest brains of any animal on the planet.  A fully grown male’s brain on average weighs 7.7 kg (17 lbs), and has a volume of 8000 cubic centimeters (2.1 gallons).  For comparison, a typical human brain is 1300 cubic centimeters (1.4 quarts). 

Does this mean sperm whales are smart?  Simple brain size isn’t the whole story when it comes to intelligence.  Given the size of an adult sperm whale, their brain-to-body size ratio is much less than that of a human.  Brain-to-body size itself isn’t the whole story, either. Another factor is gyrification, which is basically how wrinkled a brain looks.  This wrinkling is associated with a species’ intelligence. A study published in 2007 notes that whale brains surpass even humans in gyrification, and many species, including the sperm whale, display actual elements of culture.  It concludes that these species display cognitive abilities comparable to primates.

3: Collapsed Lungs Are Business as Usual

As previously noted, sperm whales dive deep to hunt for food.  Tagged sperm whales in a 2006 study dived on average 400 - 1200 m (1300 – 3900 ft) for 40-50 minutes.  Accounts exist of sperm whales diving for up to two hours.  Evidence implying very deep dives exists, as well.   A sperm whale caught in 3000 m (10,000 ft) deep water had a bottom dwelling shark in its stomach.   The water pressure at such a depth is enough to crush a car.  Sperm whales are built to take this, however. They have flexible ribcages which allow their lungs to collapse at high pressure.  Additionally, metabolism slows during deep dives to reduce oxygen consumption.  Sperm whales are also well adapted for deep diving at the cellular level.  Their muscles contain large amounts of myoglobin, which stores oxygen.  This keeps the muscles oxygenated underwater.  Sperm whale blood itself similarly contains large amounts of red blood cells, which are diverted towards critical organs to keep them from asphyxiating. 

2: Eyes Are Optional

Most sunlight striking the ocean only reaches about 200 m (656 ft) underwater, though small amounts can be detected as low as 1000 m (3300 ft).  As we’ve already established, sperm whales routinely dive much deeper than that.  Of course, they have their echolocation to find and capture prey, one the most common items being squid.  Paradoxically, squid are poor targets for echolocation.  Aside from their beaks, the rest of their bodies are believed to be too similar to water to really “stand out.”  Despite this, sperm whales apparently manage, as completely blind sperm whales have been found healthy and well-fed. 

While clearly not required, sperm whale eyes may not be totally useless, either.  They’re actually the largest eyes of any toothed whale, despite their proportionately small appearance.  Also, all whale eyes are better adapted to low light conditions than human eyes, for example featuring a reflective layer behind the retina similar to cats.  It has been hypothesized that sperm whales can use their eyes make out the silhouettes of prey against the surface from below, something that is much easier to do than looking forward or down to spot prey at depths.

1: Loudest Animals on Earth

Sperm whales have been established by researchers as the loudest animals on Earth.  Their echolocation clicks can be heard as far as 10 km (6 miles) away in water.  Males clicking near the surface can sometimes be heard by observers on boats as far away as 50 meters (164 ft). Sperm whale clicks have been measured at 230 decibels in water.  Some scientists believe that they’re powerful enough to stun prey, although this is unproven. 

A 230 decibel sound in water would be 170 decibels on land.  Consider that 150 decibels, about the equivalent of a jet taking off, can be enough to rupture eardrums.  170 decibels may not seem much louder; however the decibel scale is logarithmic, with every 10 additional decibels being perceived as roughly twice as loud by human ears.  Therefore a sperm whale clicking on land could be perceived as roughly four times louder than a jet taking off.  


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