When you think of the "macho men" in the shark family, who comes to mind first?
It may be a bull shark that sneaks into fresh water to attack humans but makes the great white shark back the pot, or the tough prehistoric overlord "megalodon".
The prehistoric overlord "Megalodon" is a famous macho man in the shark family
And the shark we are going to talk about today is not in the ranks of "macho men", and even said that it can be regarded as the "shame" of the shark family.
Because this guy lived to be 156 years old to mate, he was very lazy, he swam very slowly, and even sacrificed his eyes in order to be able to eat. So, who exactly is this shark?
The "Buddha-lineage" Greenland sleeping shark
The shark family has always been important in the evolutionary history of life on Earth, although they have always been the "second oldest in ten thousand years" before, but it does not prevent them from saving the fire until now.
There are many sharks in the world today, and they can be divided into 8 orders and 25 families, the eight orders are sixgill sharks, porbeagle sharks, true sharks, tiger sharks, horned sharks, sawsharks, flat sharks and whiskered sharks. In some classifications, spiny sharks are also listed separately.
There are still many members of the shark family
Among them, the sharks are more special, they often live in warm water, cold water areas or deep sea, and the one living in the cold water deep sea is like the "Eskimos" in the shark population. The Greenland sleeping shark we want to introduce today is the "hardy king" of the horned shark.
According to the data, this guy can reach a maximum length of about 7 meters and lives in the waters around Greenland and Iceland.
The hardy king of the shark family, the Greenland sleeping shark
Sometimes, in the deep waters of the Arctic, you can also find the shark. Perhaps because they don't want to attract attention, Greenland sleeping sharks like to hide in deeper waters.
In warm climates, they hang out in water depths of about 180 to 550 meters. When you don't want to be disturbed, you will swim to a depth of about 1,000 meters or more. Because previously, someone near the coast of Georgia found this guy "sleeping" in the deep sea at a depth of 2200 meters.
Divers come across Greenland sleeping sharks lounging
The reason why I want to talk about sleeping is because this guy is notoriously "chronic". Although it is a match for the size of the great white shark and has sharp teeth, the Greenland sleeping shark does not like to take the initiative, but likes to "wait for the rabbit".
So if you dive into the deep sea to observe its predation process, you will find that this guy is swimming slowly and leisurely in the sea, looking like a "lazy man", which may be the main reason why people call it a sleeping shark.
Greenland sleeping sharks are swimming slowly
In addition, the eyes of the Greenland sleeping shark look dull compared to those of other sharks. And when we look deeper into it, we will find that it does not rely on its eyes to hunt, in order to be able to guard the rabbit and attract prey to the door, it sacrifices its own eyes. So, what's going on here?
In order to fill the stomach, choose to sacrifice the eyes
It turns out that there are some copepods near the eyes of the Greenland sleeping shark, and the presence of these animals will affect its vision, and also make its eyes look like "worms", which is very scary.
According to the data, these animals parasitize its eyes, slowly destroying its cornea, and eventually causing it to suffer from the embarrassing situation of partial blindness.
Greenland sleeping sharks parasitize copepods in their eyes
However, for copepods to "eat" their eyeballs, the Greenland sleeping shark does not care, but shows a very welcoming attitude.
This is because it lives in the deep sea for a long time, and it is difficult for sunlight to reach here, making it dark all around. In this case, eyes without "night vision" are not useful for Greenland sleeping sharks. So more often than not, it relies on smell and touch for hunting.
Greenlandic sleeping sharks live in quite dark deep seas
And because copepods can emit faint "biolight," they act like "bait" to help Greenland sleeping sharks attract the attention of deep-sea phototaxis creatures.
This is actually very similar to the ugly salmon, because this guy also relies on the "luminator" above his head to attract prey, and then when he comes closer, he opens his mouth and swallows.
Deep-sea catfish also use overhead luminaires to attract prey
It can be seen that the Greenland sleeping shark sacrificed its own eyes to make this transaction, in fact, it is still very cost-effective, after all, its living environment determines that vision is not so important. This guy can often rely on this method and slow and leisurely feints to eat a lot. It is not a picky eater and eats almost anything, like squid, sea urchin, starfish, and so on.
It is worth mentioning that many researchers think that this guy may also have accelerated swimming behavior, but it has not been observed by us. Because people have also found dolphins, seals, cod and other creatures in its stomach, you must know that the swimming speed of these creatures is still relatively fast, so just relying on the tactic of "waiting for the rabbit", Greenland sleeping sharks should not be able to eat them.
The behavior of Greenlandic sleeping sharks eating dolphins has led scientists to speculate that it can swim faster
In addition to being very interested in the "slow-motion hunting strategy" of the Greenland sleeping shark, people are also very curious about its age and the longevity of the "unusual fish". There are even studies that show that this guy does not live to be sexually mature until he is 156 years old, and then he can mate, is this true?
Are Greenland sleeping sharks really that long-lived?
In general, judging whether a shark has entered the stage of sexual maturity is mainly based on its length. Like the familiar great white shark, males mature only when they grow to about 350 cm to 410 cm, while females grow to about 450 cm to 500 cm.
Schematic diagram of the body structure of a great white shark
The Greenland sleeping shark grows very slowly in length compared to other sharks. As early as the thirties of the last century, marine biologists marked about 400 Greenland sleeping sharks in the waters of Greenland, observed their body size changes, and found that these guys who eventually grew into "Big Macs" only grew about 1 cm per year.
However, slow growth does not affect its sexual maturity age, females often need to grow to 400 cm to become sexually mature, and at this time its age has reached about 156 years old.
Greenland sleeping sharks need to be 156 years old to be mature
After entering sexual maturity, Greenland sleeping sharks embark on a path of slowly finding a future partner. Since it is very long-lived and can live to be around 400 years old, it is normal to be single for 50 years after sexual maturity.
So why do they live so long? And how do people measure their age?
First, let's look at the reasons why Greenland's sleeping sharks live long.
According to research, the lifespan of Greenland sleeping sharks may be related to the temperature of the sea where they live and their daily activities. In terms of temperature, the waters where Greenland's sleeping sharks live are relatively cold, generally between 1 and 12 degrees Celsius, and sometimes break below zero.
Greenlandic sleeping sharks live in very low temperatures
In this environment, the metabolism of the Greenland sleeping shark is quite slow, and it is this metabolism that further slows its growth rate. According to genetic research, cold environments can effectively activate anti-aging genes in organisms and help them prolong their lives.
From the perspective of daily activities, the Greenland sleeping shark is "unhurried" most of the time, and the range of activity is not large. This also helps them maintain a slow metabolism and thus become the "old birthday" in the ocean.
A slow metabolism may be the secret of its longevity
Second, let's talk about how scientists found their age.
Previously, Julius Nelson from the University of Copenhagen in Denmark and his research team used carbon 14 dating to age it. Subsequently, they published the paper in the prestigious journal Science in 2016.
Scientists used carbon-14 dating to age Greenlandic sleeping sharks
According to the data, the researchers used radiocarbon dating to observe the lens nucleus in the eyes of Greenlandic sleeping sharks, because the protein of this structure is often present shortly after birth. And the final result shows that these guys can really live to be more than 400 years old!