#physeter

Hi guys, another long silence I know. It’s busy with the train driver’s course - on top of regular driving I’ve had training for and taken a couple more exams (all passed, thankfully). It’s coming to an end though - within a few months I should be driving independently! Looking forward to it, as well as being able to pick up drawing again.

Sperm whale (Physeter macrocephalus)

Sperm Whale or Cachalot Physeter macrocephalus

Sperm whale (Physeter macrocephalus)

Sperm whale (Physeter macrocephalus)

Endangered cetaceans, part 17

Sperm whale/Cachalot, Physeter macrocephalus

In this post, I will refer to them as cachalot, because while sperm whale is the official English name, it's a very... unfortunate name.

Beware, this will be a long post, because I can’t just talk about their conservation status without first going into detail about this awesome animal.

The sperm whale, or cachalot, is probably the most unique and recognizable of all whales. Unmatched in size by other toothed whales, their only living relatives are among the smallest of all cetaceans, and their large relatives (like Livyatan), are long extinct.

It is not only one of the culturally most important whales to humans in general, it's also my favorite large whale, so prepare for a lengthy post.

While nowhere near the size of a blue whale in body mass or length, the cachalot's brain is the largest on Earth, possibly of all time (since dinosaurs had comparatively small brains, and the brains of baleen whales, elephants and smaller toothed whales don't even come close).

Still, while brain-body mass ratio isn't a direct indicator of intelligence (for example, going by brain-to-body mass ratio, sharks should be smarter than hippos. Ants, shrews, and frogs should be smarter than elephants, and small birds and mice should be smarter than humans), the cachalot's brain is "only" five times larger than a human's, while the whole animal is 500-1000 times the size of a human.

One thing that makes the cachalot stand out and which most people might now know about, is their unique blowhole. Baleen whales have two "nostrils" on the back of their head, while toothed whales have a "C-shaped" single blowhole in the same place, the round shape facing towards the back.

The cachalot however, has a single left nostril on the front of its head. It is the only cetacean today which doesn't have its blowhole on the back of its head. Interestingly, their only two living relatives, the dwarf and pygmy sperm whales, have their blowholes on the back of the head, like any normal toothed whale... but backwards!

The picture above shows humpback, killer whale, cachalot and pygmy sperm whale, all heads pointing in the same direction.

Another thing making them stand out are their teeth - because they only have them in their lower jaw! The upper jaw only has sockets for the lower jaw’s teeth to go in.

Their flukes are also unique, stubby with rounded tips, and softly jagged edges. I’m not good at distinguishing the large whales by only their backs or flukes, but the cachalot (and the humpback) are always easy to recognize by their flukes.

The cachalot is found nearly all over the planet, with the few exceptions seen in the map above. White areas show where there are none, dark areas show the highest concentrations of the whales.

The species is considered vulnerable by the IUCN, the status between "endangered" and "near-threatened".

They are deep divers, the second deepest diving mammal on Earth, only beaten by the Cuvier’s beaked whale. They can dive up to two kilometers (well over a mile) below the surface, and hold their breath for over an hour, perhaps up to two hours. For comparison, most whales and dolphins can only hold their breath for 5-10 minutes.

Down in the depths, the cachalot is the most certified badass to ever exist. I have to say it, they are cooler than the Megalodon, Basilosaurus, Mosasaurus and Liopleurodon combined. And while they are not only the largest toothed predator to exist today, they might be the largest of all time, just beating the Megalodon (an enormous shark) and Basilosaurus (one of the first large whales) in length.

The largest Mosasaur reached 17 meters, Basilosaurus reached 18 meters but was very slender and lightweight, and the Megalodon maxed out at 18 meters as well, but very large females could match a male cachalot in weight, at around 58 tons. The largest cachalots grow to 20.5 meters long. (The Liopleurodon by the way, was only the size of a killer whale. Sorry, WWD fans, they got me too.)

And down in the dark depths, in the feeding range of the cachalot which extends from 300-2000 meters down, they feed on giant and colossal squid. That’s right, two of the most terrifying animals on Earth - are this whale’s dinner.

The battle between these two creatures is often depicted in art, but has never been seen or filmed. We can only imagine what it looks like, because of scars on the whale’s head, and the resulting squid parts in its stomach.

The left photo shows the stomach contents of a cachalot. Sadly, there are plastic bags there, but you can also see squid bodies and beaks in droves.

Their main diet is medium-sized squid however, and they occasionally eat deep-dwelling fish, so we can imagine that only the largest whales will go after a giant or colossal squid. (The latter of which, has razor-sharp rotating hooks on its ten arms.)

In the Antarctic however, this seems to be one of their main prey items.

14% of the squid beaks found in the stomachs of these sperm whales are those of the colossal squid, which indicates that colossal squid make up 77% of the biomass consumed by these whales. 

It is while hunting in the pitch-black depths that their large melon comes into use. All toothed whales have a melon in order to “see” in dark and murky waters, by creating clicking sounds that reverberate through the melon, and gives them a “sound image” of what is ahead (like how microbats hunt insects at night).

River dolphins for example live in such murky water that their eyes have nearly disappeared, as they live almost entirely by echolocation. The cachalot, as well, can’t see a thing down in the deep, and relies on its sonar to hunt.

The cachalot’s sonar is so powerful however (it’s officially the loudest animal on Earth), that it may not only be used to “see” its surroundings, but also as a weapon. There is a hypothesis, that with these powerful sound waves being sent out in the water, they can effectively stun prey. Being “clicked” by baby cachalots can supposedly make your insides jiggle, while an adult’s click feels like being kicked in the chest by a horse. [Another video]

The cachalot was one of the main targets for commercial whalers, beginning in the 18th century and then being overtaken by modern practices and machinery in the early 20th century. They were especially sought-after as they not only had blubber, like all whales, but also a special substance - “spermaceti” - in their heads.

The name “cachalot” derives from their large head, and the scientific name “macrocephalus” literally means large head as well. This enormous head is a vastly expanded melon, the fatty soft tissue on the front of every toothed whale’s head, which baleen whales lack entirely.

Back in the 1800s, whalers thought the white, waxy substance inside the cachalot’s head was literally its sperm - and thus the name, “sperm whale”.

The whales in the industrial whaling operations were not eaten, they used their blubber - and in the case of the cachalot, the spermaceti - for oil, wax, and other resources. (They even used baleen from other whales to put in corsets, mistakenly called “whalebone”.)

It is believed that before whaling, the cachalot amounted to over one million globally, and that by 1880, they had been reduced by 29%. A century later, by the end of commercial whaling, roughly 360 000 whales remained. At its peak in the mid-20th century, about 25 000 cachalots were killed every year.

This huge pressure on the species is now gone (from what I have seen, if the large-scale commercial whaling hadn't halted and stopped but continued to this day in the levels of the early 1900s, all large whales would be extinct today), but other than their slow reproductive rate which makes a comeback very slow, there are new threats which threatens its recovery and ultimate survival.

Today, there is still small-scale hunting going on of the species. They are taken from small boats around Indonesia, as seen in the photo, at most in the tens, but it does not happen every year. Japan also has a maximum of ten allowed cachalot kills per year.

Like all other cetaceans, they are at risk for being entangled in abandoned fishing gear, leading to large wounds, loss of limb, and even drowning.

This threat is greatest in the Mediterranean, but the whales are affected all over the planet. Like other whales, they have been found with high levels of toxic contaminants in their tissue.

The effects of noise on Sperm Whales are also uncertain. Some evidence suggests that they are highly sensitive to noise while other studies have found little or no effect. To date, all published studies of Sperm Whales and noise focus on short-term behavioural effects. Avoidance of sonar and seismic surveys has been observed but no mortality has been documented.

While the species overall is considered vulnerable, the Mediterranean population is listed as endangered.

Cachalots used to be common in the Mediterranean, large "pods" of up to 30 individuals being found in the Straif of Messina in the 1940s-50s. Fifty years later, only fifteen whales could be found there in an entire year of searching.

One good sign is that the number of strandings in Italy have declined substantially. In 1987, nineteen cachalots were found dead on the shores, at least 13 of which had been entangled with driftnets. After that, it declined to an average of 4-5 animals per year.

These are two of 13 cachalots that mass-stranded in Germany in early 2016. Several of them had their stomachs full of plastic and other garbage.

Still, these driftnets (intended for swordfish and tuna) pose the greatest threats to this subpopulation. Between 1971 and 2004, a total of 229 cachalots were found dead or entangled in the waters of Spain, France and Italy (90% of which were after 1986). Most of the stranded, dead whales had been entangled, as either parts of nets or net-shaped wounds could be seen on the carcasses.

Driftnet fishing is the biggest threat to the survival of cachalots in the Mediterranean, while other threats include disturbances from intense shipping traffic ("highways of the sea"), collisions with large vessels (more than 6% of 111 dead cachalots in the 80s and 90s were killed like that, and 6% of 61 live individuals bore wounds or scars from a vessel strike), underwater noise from oil and gas prospecting (through seismic airguns), military operations, illegal dynamite fishing, and seismic surveys (which has been a daily occurence since 2007).

Other than that, the species seems to be relatively safe, but these threats in the Mediterranean exist to some level in all oceans of the world.

https://en.wikipedia.org/wiki/Sperm_whale

http://www.iucnredlist.org/details/41755/0

http://www.iucnredlist.org/details/16370739/0

https://faculty.washington.edu/chudler/facts.html

https://dispatchesfrompangaea.wordpress.com/2012/07/17/sperm-candle-spermaceti-sperm-whales-moby-dick/

https://news.nationalgeographic.com/2016/03/160331-car-parts-plastics-dead-whales-germany-animals/