The oceans are the mystery of mysteries of our planet. Although 99% of the total biosphere is found inside it, we only know a scant 5%. In the year 2000, an ambitious international program was launched that for a decade sought to shed light on the diversity, distribution and abundance of life down to 5,000 meters of depth. The program was named the Census of Marine Life , and involved 2,700 scientists from more than 80 countries. It was an unprecedented study in history, in which 540 expeditions were carried out at a cost of 560 million dollars, and which discovered previously unknown beings and phenomena, such as a new species of a type of Jurassic shrimp ( Neoglyphea neocaledonica ) that believed to be extinct 50 million years ago.
One of the most striking discoveries happened in 2002, when a team of researchers decided to study one of the most famous and at the same time most unknown beings in the ocean: the great white shark. And discovered something really surprising. Every year during the northern hemisphere’s winter, white sharks off the American Pacific coast gather at a mysterious location halfway between Hawaii and Baja California. The area has a radius of 250 km and researchers have sarcastically baptized it with the name of the White Shark Café. That is like a desert in the water; there is nothing of interest there. So why do they go? Nobody has a clue.
Some biologists think that it has to do with the moment they mate, because depending on the sex they move in one way or another: while the females swim following straight and predictable movements, the males go up and down along the water column . Are they looking for a partner? In 2018 it was discovered that there, deep underground, there is a rich and diverse food chain. Will white sharks go once a year to put on their boots? And for that they travel for more than 100 days on the high seas, until they reach a place in the middle of nowhere?
Be that as it may, when the meeting is over the males return to shore. The curious thing is that the females lose track for a whole year ; perhaps they hide to give birth. Next thing we know, the newborns show up in the waters off southern California, the great white shark’s feeding ground, and stay there until they’re big enough to rejoin their elders.
What is mysterious is that it is not typical behavior of white sharks: what the North American Pacific sharks do is not done by their Australian cousins , who search for food along the southern coast of that continent without following a pattern of behavior or gathering in groups. a coffee’. And the Atlantics? About them our ignorance is even greater. They are known to travel to a spot in the middle of the Atlantic Ocean, wander around and dive to depths of up to 900m /s every day, but we have no idea what they actually do. When an autonomous underwater vehicle was sent to spy on them at night, footage showed that they appeared to be resting. “I hesitate to say ‘sleep’ because it is difficult for us to determine if and when these sharks sleep,” one of the researchers commented.
In 2016 it was discovered that a female whale shark, the largest fish in the world -it can reach 12 meters in length and dive to a depth of 1,900 meters-, made a migration of more than 20,000 km through the Pacific : it remained in Panamanian waters for 116 days, then swam to Clipperton Island (France), passed near Cocos Island (Costa Rica) and continued on to Darwin Island in Galapagos (Ecuador), a place that must have a special interest for sharks, because many gather there and we don’t really know why. Then the signal from the device he had installed disappeared and after 235 days of silence he reappeared in southern Hawaii. From there it continued to the Marshall Islands until it reached the Mariana Trench near Guam in the Western Pacific. Why he made such a migratory journey is a mystery. In fact, it is not known why they do it.
Added to this is that in the open sea there are very few visual signals, so how do they know where they are going? We don’t know how they find their way through the ocean , what environmental cues they use, and how exactly they detect those cues. There are suspicions that sharks, like other species, can sense the Earth’s magnetic field and use it as a navigation tool. It is also believed that their highly developed sense of smell – they can smell a drop of blood from 700 meters away – may be another navigation tool, just like sound, but these are just extrapolations of what is known about how they perceive the world. around it.
Of sharks we know very little; we don’t even know how many species exist. Thus, the discovery of the so-called ninja shark ( Etmopterus benchleyi ) was announced in December 2015; in 2013 a new species of hammerhead shark ( Sphyrna gilberti ) was identified off the coast of South Carolina; and a new species of walking shark (Hemiscyllium halmahera), made headlines after researchers discovered it on a reef in Indonesia in 2013. Sharks remain one of the great mysteries of the seas.