Unicorns are animals of Western legend that are said to resemble a horse with a spiral-shaped horn on their head. Although Europeans never saw a living unicorn during the Middle Ages, the priceless "horn of the unicorn" occasionally appeared on the market. Now we know that the prototype of the unicorn is the Indian great unicorn rhinoceros, and the so-called unicorn horn is actually the tusk of a narwhal. Today we will introduce you to the "unicorn of the sea" - narwhal.
narwhal
<h1 class="pgc-h-decimal" data-index="01" > a close relative of beluga whales</h1>
Narwhals and beluga whales form the only two surviving members of the Narwhal family. Narwhals with "horns" removed look a lot like beluga whales, they are medium-sized cetaceans with a body length of about 4 meters. Neither dorsal fin is available to swim under the ice floes of the Arctic Ocean. Their snouts are extremely short, their foreheads are high and raised, and they have melon-shaped adipose tissue inside, which is their echolocation organ. Their cervical vertebrae join normally, rather than fused like most cetaceans, so they all have necks, albeit short, unlike other cetaceans.
Narwhal body size versus humans
The most significant difference between a narwhal and a beluga whale is its "horn", which is actually its teeth. This tooth is the left canine tooth of a narwhal, sticking out of the lips, growing forward in a left spiral, growing for life, about 1.5-3.1 meters long; hollow inside the tooth, weighing about 10 kg. With the exception of this tusk, the other teeth of the narwhal are not born in the alveolars, and although it belongs to the suborder Dental Whale, it has no teeth in its mouth. Usually only males have tusks, 0.2% of males have two tusks, i.e. right canine teeth also grow out, while 15% of female whales also grow tusks.
Another difference is body color. As the name suggests, beluga whales are white and are the only white whales. The narwhal's ventral surface is white, and the back is a mottled black pattern on a white background, the pattern is the blackest when the juvenile whale is born, and the older it grows, the whiter it becomes, and some elderly male whales are almost completely white, which is difficult to distinguish from beluga whales except for tusks.
Ventral and side view of narwhals
The narwhal family, where narwhals and beluga whales are located, together with the dolphin family and the porpoise family, constitute the dolphin superfamily of the toothed whale suborder. The Narwhal family is closely related to the porpoise family, and their common ancestor was separated from the dolphin family 11 million years ago. Narwhals and beluga whales originally lived in tropical waters, migrating to the Arctic during the Late Cenozoic (~3 million years ago) as the marine food chain changed, and have since made their home here.
Narwhals and beluga whales
<h1 class="pgc-h-decimal" data-index="02" > unicorn horn</h1>
The tusks of narwhals can be said to be a miracle of nature, and people who have never seen narwhals can hardly imagine that this is a real creature, which is why so many people in ancient Europe regarded this tusk as the horn of a unicorn. Until recently, zoologists couldn't figure out what the tusk was really for. Many hypotheses have been proposed, such as that narwhals use their tusks to dig clams on the seabed to eat, or pierce the ice to breathe air. In fact, the tusks of narwhals are relatively fragile and difficult to use as a tool for digging soil or breaking ice.
In 2014, a team of researchers from Harvard University confirmed that the narwhal's tusks are actually a sensory organ. The tooth enamel layer of the tusks is covered with pores, there are thin tubes leading to the inside, and there are many nerve endings in the pulp that connect to the brain, which are extremely sensitive to changes in sea temperature, pressure and salinity, which can help male whales find food, breathing holes and female whales in heat. The researchers found that a narwhal can taste the salinity of water with tusks, and when it puts its tusks into water of different salinities, its heart rate changes significantly.
Since male whales usually have tusks and females don't, it's easy to think that tusks are associated with competition for sexual selection, with some suggesting that males use tusks as a weapon to compete for a mate, or a tool to show off and show off, and often see the ritual of male whales rubbing their teeth against each other. Now research confirms that male whales are actually exchanging physical and chemical information collected from water with each other, a form of intraspecific communication, and have nothing to do with wife snatching.
The "tooth-rubbing ceremony" of the male whale
In 2017, WWF researchers discovered a new use for narwhal tusks, which, from images taken by drones, can track cod with tusks, and when the cod is close to the tip of the tooth, it quickly and forcefully knocks the cod to make it temporarily unconscious, and then opens its mouth to swallow it.
The narwhal has a short snout and no teeth, and it can only wait for the fish to swim closer and suck it into its mouth. When the hunk swam close to the school of fish, the fish had already been frightened away. Therefore, the narwhal sneaks in with its tusks, suddenly knocks the fish unconscious and then swallows it, which is indeed a good way to catch the fish.
<h1 class="pgc-h-decimal" data-index="03" > inhabitants of the Arctic</h1>
Narwhals are inhabitants of the Arctic Ocean and, like beluga whales, prefer the most icy seas, and are the northest-distributed whales. Narwhals have migratory habits, but when it is cold, they swim north in search of seas with a lot of ice floes. In autumn and winter, it inhabits the offshore waters of Baffin Bay and Davis Strait, where open water is limited and covered by more than 95% of the ice floes. Under the ice floes, benthic organisms, especially flounder, are particularly abundant, which are the favorite prey of narwhals.
Distribution of narwhals
When the sea ice melts in the summer, the narwhal migrates south to the ice-free waters off the coast, spending two months here, where it feeds mainly on cod, followed by flounder. Autumn and winter are more abundant and easy to catch, contributing more to the nutrition of narwhals, and summer is a relatively food shortage period.
Narwhals can dive to depths of more than 1,500 meters and hold their breath for more than 25 minutes, making them the most diving sea beasts in the Arctic. It dives more than 15 times a day to 800 meters or deeper, accumulating more than 3 hours of diving time. Narwhals feed on benthic creatures and need to breathe air, and their strong diving ability solves this contradiction very well.
Narwhals prefer ice-packed waters
<h1 class="pgc-h-decimal" data-index="04" > threatened by global warming</h1>
The greatest natural enemy of narwhals is killer whales. Scientists filmed a video in 2014 of killer whales trapping them in shallow waters and hunting them, killing more than a dozen narwhals. The narwhal has to find a way to escape to the deep sea and use its diving advantage to escape the killer whale. Sea ice is an effective inhibitor of killer whale activity, so killer whales mainly harm narwhals in the summer.
Killer whales hunt narwhals
Once the narwhal arrives in its ice-rich wintering grounds, the killer whale struggles to help it, and the polar bear becomes its number one natural predator. Polar bears mainly ambush around breathing holes, attacking narwhals that are exposed to the water for ventilation. Polar bears predominantly hunt juvenile whales, and adult narwhals are too big for them.
Polar bears nibble narwhals so that they are left with tusks
Although the narwhal tooth was once valuable in the past, it has never been a major commercial whaling target, probably because its distribution is too far north. Now Westerners' understanding of the value of narwhal teeth has gradually returned to rationality, just as an ordinary art collection, no longer giving it special witchcraft or medicinal value. At present, it is mainly inuit that some narwhals are killed every year, and the annual number of kills is about 1,000. Experts have assessed that there are about 170,000 narwhals worldwide, which are generally non-threatened species, which is a minuscule amount of hunting.
The biggest threat to narwhals is warming. Warming has expanded the area of the ice-free sea, greatly increasing the chances of narwhals encountering predators. As killer whales entered Hudson Bay, large numbers of narwhals, especially juveniles, were slaughtered. In recent years, inuit have also found it much easier to encounter and capture narwhals than in previous years.
The tusks of narwhals have commercial value
Experts have assessed that narwhals are among the most sensitive organisms to global warming, more sensitive than polar bears, mainly due to the higher habitat needs of narwhals. Polar bear breathing and hunting are done on the ice, while narwhals not only have to breathe on the surface of the sea, but also eat flounder on the seabed, and the distance from the breathing hole to the feeding place is controlled within 1450 meters. Therefore, the narwhal can only live in the offshore waters of the Arctic Ocean, with a water depth of several hundred meters, and the ocean-going area is not suitable for its survival. Polar bears can survive near the North Pole for a long time, narwhals can't.
The warming of the climate delays the freezing of the waters around the Arctic Ocean in autumn, and in the winter, because the climate is far more variable than before, sudden low temperatures, no wind and other weather conditions can easily freeze the breathing holes, resulting in narwhals being unable to breathe and choking to death. Narwhals need to have breathing holes that are at least half a meter wide, and if there is a lack of suitable breathing holes, narwhals will be forced to abandon some high-quality feeding points that are too far away, which will inevitably lead to a decline in environmental capacity in the long run.
Narwhals surface to breathe
Some are optimistic that since narwhals migrated from the tropics during the Pliocene, there should be some flexibility in adapting to the environment. However, the premise is that the environment does not change too quickly, there must be enough buffer, but now the climate warming caused by human activities is 50,000 times faster than nature! The coastal waters off the Arctic Ocean are the last home of narwhals, they have no way back, if this area becomes no longer suitable for narwhals to live, then this magical "marine unicorn" will disappear forever, so it is time to take action to protect them!