They have 0 eyesight but can live to 400 years: it turns out that there are also so many strange whale sharks in sharks - the fish giant Garimantan lighttail shark - pocket cat shark Greenland sleeping shark - polar life star barramundi shark - sea cheetah gray trident shark - double "shark grid" Jushi mustela shark - positioning master fluffy shark - low-key "star" epaulette shark - "walk" out of the predicament longtail shark - whip hunter leaf whisker shark - ambush master wrinkle shark - like eel non-European pointed snout shark - deep sea "goblin" shark survival status

Sharks are arguably the most fearsome animals in the ocean. The ferocious image of the great white shark in the movie is a childhood shadow for many people, but you may not know that the types of sharks are far more abundant than imagined.

There are currently about 500 species of sharks known to mankind, and in addition to the classic great white shark image that we are most familiar with, there are many sharks that you did not expect. They may look weird or have special skills. The following 12 kinds of sharks with different characteristics will definitely subvert your imagination of sharks.

Image source: Network

First, let's take stock of the most sharks:

<h1 class= "pgc-h-arrow-right" > whale shark – the behemoth of the fish</h1>

Endangered: Endangered

Image source: Wikipedia

The 18.8-meter-long whale shark (Rhincodon typus) is the largest fish in the world, almost on par with sperm whales. Not to mention their huge size, but they are actually only plankton-feeding filter-eaters, filtering through about 4.5 million liters of seawater every day and sifting through plankton through a specialized structure called dermal denticles.

Gills of whale sharks. Image source: Network

Sometimes, whale sharks also want to improve their diet, for example, when the tuna is trying to drive the small fish together, and is about to feast, a whale shark actually comes to "rub rice" and swallows the rations of a group of tuna.

Image source: BBC

<h1 class= "pgc-h-arrow-right" > Kalimantan lighttail shark – pocket cat shark</h1>

Endangered: Data Deficient (DD)

Illustration and specimen of the Kalimantan lighttail shark. Image source: shark-references.com

Think sharks are big guys? The world's smallest shark, the Kalimantan light-tailed shark (Apristurus sibogae), can be easily held in the palm of your hand. Belonging to the family Scyliorhinidae, it is similar in length to a kitten, only 21 cm, and its whereabouts are as mysterious as your master. The only specimen was collected at a depth of 655 metres in the Makassar Strait.

<h1 class= "pgc-h-arrow-right" > Greenland Sleeping Shark – polar life star</h1>

Endangered: Near Threatened (NT)

Image source: WWF

Size is not important, living long is king. The Somniosus microcephalus, which belongs to the somniosidae (commonly known as sleeping sharks), is the longest-lived vertebrate in the world known to date, reaching a staggering 400 years. Wandering in the Arctic Ocean, they can adapt to sub-zero temperatures, sleepwalking to maintain a "Buddhist" state of life - only 1.22 kilometers per hour, which can be said to be a real "turtle speed" (turtle: I am much faster than it!). ）。

The Greenland sleeping shark, which can reach a length of 7.3 meters, grows only 0.5-1 cm per year, and such a slow metabolic rate is likely to be the secret of their longevity. The sluggish Greenland sleeping shark is dominated by carrion, even the remains of narwhals and beluga whales (yes, even hunting is too lazy to exhaust).

If you look closely into the eyes of the Greenland sleeping shark, you'll most likely notice something strange attached to it, a copepod parasite (Ommatokoita elongata). The Greenland sleeping shark, whose eyeballs are gnawed at by this parasite, cannot see anything and forages mainly by smell. But some scientists have speculated that the two are mutually beneficial symbiotic, and that the parasite may help the host attract prey by emitting biofluorescence, although this hypothesis has not been confirmed.

Greenland sleeping shark eye parasite. Image source: DinoAnimals.com

<h1 class = "pgc-h-arrow-right" > barramundi shark – a cheetah in the sea</h1>

Image credit: Florida Museum

The Isurus oxyrinchus, also known as the grey mackerel shark, is the fastest shark in the world, reaching 50 km/h, and even a record of 74 km/h. The speed of the barramundi shark has a lot to do with its prey, such as the same predator, agile tuna, porpoises and so on.

To learn the secret of the shark's astonishing swimming speed, engineers have begun to study its skin. We know that swimsuits with shark skin special shield scales have helped swimmers speed up successfully, so engineers want to use the same principle to reduce friction, increase speed and agility for vehicles.

Shark shield scale structure, not only reduce resistance but also antibacterial. Image source: Oceanographic museum of monaco

After taking stock of the best sharks, let's meet some sharks with strange personalities.

<h1 class = "pgc-h-arrow-right" > grey trident shark – double "shark grid"</h1>

During the day, triaenodon obesus will lie lazily on the seabed near the reef together, and passing fish will use their skin as a "cat scratching board" and even swallow their anger when harassed by passing sea lions.

But when night fell, a dramatic scene occurred - these guys who were still "soft persimmons" during the day suddenly came back to life in blood, killed, and began a revenge-style "sweep". The weak fish hid in the reef, afraid of being discovered.

However, even if hidden, the gray trident sharks, transformed into "gangsters", will track their presence through an electroreceptor called the ampullae of Lorenzini (all living creatures generate electric fields, while sharks can detect a weak current of one millionth of a watt). Once the prey is spotted, a large flock of gray three-toothed sharks will swarm up like wolves swooping in.

Attacking grey trident shark. Image source: BBC

However, when the first rays of morning light shine into the reef, the "demon" switch of the gray three-tooth shark will be turned off again, turning into an indisputable and well-behaved appearance.

<h1 class= "pgc-h-arrow-right" > The Mustela Shark - Positioning Master</h1>

Unlike the gray trident shark, which has no "majesty" of the shark during the day, the Galeocerdo cuvier (commonly known as the tiger shark) in the domineering tiger stripe is completely murderous and exposed, and even preys on its own kind, and is considered "one of the most dangerous sharks". However, this carnivorous beast is not particular about food at all, and the recipe even includes all kinds of artificial waste that you can't imagine (such as metal sheets, plastic, sacks, etc.), so it got the name of "ocean trash can" (think about it, stomachache, obviously it is a pot for human beings to make marine garbage...). ）。

Don't look at the tiger sharks when they eat sloppily, in fact, they are also the "positioning masters" in the animal kingdom, born with a precise earth's magnetic field "navigator", and regularly migrate about 7500 kilometers back and forth on a fixed route every year - to the Atlantic Ocean in the summer and back to the Caribbean for the winter. The purpose of this migration remains an unsolved mystery.

The behavior of the grey trident shark and tiger shark is just weird, and the skills displayed by the "little cute" who will be introduced next will make you "shine".

<h1 class = "pgc-h-arrow-right" > fluffy shark – a low-key "star"</h1>

Endangered: Harmless (LC)

Image source: shark-reference

The sea is dangerous, and the smaller, fluffy shark (Cephaloscyllium ventriosum) always hides in crevices in the rocks. Although predators have difficulty spotting them, they are "bling bling" in each other's eyes. Because of love? Don't be stupid, the original seemingly low-key them, in fact, each one is born with its own fluorescence. It's just that this fluorescent can't be seen by other predators, including humans, but in the eyes of the fluffy shark it is a conspicuous bright green (love is a light, do you want green?). ）。

The principle of luminescence lies in the presence of a fluorescent protein in its skin, which will be stimulated to produce green light after absorbing blue light. The habitat of the fluff shark can be up to 500 meters deep, most of the longer wavelengths of visible light can not reach, while the shorter wavelength of blue light is less lost, even if the fluff shark converts it into green light, in the eyes of other organisms, the relatively strong blue light will also cover it up. The eyes of the fluffy shark are correspondingly equipped with a "filter", and after filtering out the blue light, you can see the green fluorescence emitted by the companion.

In order to show the world in the eyes of the fluffy shark, the researchers used a yellow filter to block out the blue light, and finally showed the long-unknown beautiful fluorescence of the fluff shark.

Special camera (a) with the normal bust under the eye (b) of the fluffy shark. Image credit: Nature

Scientists are also studying how to apply fluorescent proteins from the epidermis of the villi shark to the localization tracking of diseased cells.

<h1 class= "pgc-h-arrow-right" > epaulette sharks — "walk" out of trouble</h1>

Fluffy sharks prefer the deep sea, while another cute epaulette shark (Hemiscyllium ocellatum) prefers to be active in the shallow waters of coral reefs. The large round black spot behind its ventral fin can be said to be a big cute spot. Although it is the smallest shark in the reef, the high tide is low and low, the fish are unpredictable, and stranding is always inevitable.

What to do? Of course, you can't stand still and be dried by the sun.

Epaulette sharks have their own tricks: first they shut down some non-essential organs and brain functions to reduce oxygen consumption. Then it's time to witness miracles! Don't think too much, of course, instead of transforming into a big long leg like a mermaid, you support your body with your fins and crawl back into the water.

Little cute haven't seen the addiction? Let's see some of the high-value sharks that have a special way of predation.

<h1 class = "pgc-h-arrow-right" > long-tailed shark – whiphunter</h1>

Endangered: Vulnerable (VU)

The long-tailed shark (Alopias vulpinus) has a very windy and handsome tail fin, which is almost the same length as its body, as if wearing a long sword behind it. But at the same time, the teeth of the longtail shark are much inferior, not only small, but also weak in bite force, so the longtail fin comes in handy. When the longtail shark finds prey, it will swim quickly to the prey, first using the pectoral fin to initiate a tail flicking action, and then use the powerful tail fin to knock it unconscious. After eating this whiplash-like slash, the prey was reduced to the mouth food of the long-tailed shark.

Longtail Shark: Look at me "Godfish Flicking Tail". Image source: BBC

< h1 class = "pgc-h-arrow-right" > leaf whisker shark - ambush master</h1>

Image credit: Monaco Nature Encyclopedia

Unlike the large long tail of the long tail shark, the flattened leaf whisker shark (Eucrossorhinus dasypogon) did not intend to confront its prey, but adopted an ambush strategy. Leaf whisker sharks have a specialized whisker-like structure on their jaws, and the spots on their bodies do not seem to be attractive, but on the contrary, they can be better hidden in the surrounding seagrass and coral reefs.

Leaf whisker shark: Can't see me, can't see me. Image source: BBC

The leaf whisker shark is very good at camouflage, in addition to the appearance advantage, it is also a natural "performer". During an ambush, it wiggles its tail from side to side, mimicking a swimming fish to attract prey. When the fish are attracted by its performance, the leaf whisker shark will attack and swallow its prey at lightning speed.

Aren't these sharks exciting enough? Then dive deeper into the sea together to hunt for curiosity.

"If you can't see it anyway, you can grow it."

<h1 class = "pgc-h-arrow-right" > frilled shark – resembling an eel instead of an eel</h1>

Chlamydoselachus anguineus (Chlamydoselachus anguineus) in the 600 to 1000-meter deep sea area is a typical case of "long deviation", which has become an eel with a small dorsal fin, a length of about 1.5 meters, and up to 6 pairs of gills, which can obtain more oxygen in a low-oxygen environment. Deep-sea predation is difficult, and the frilled shark has evolved a special structure within its eyeball that can detect tiny prey like an image enhancer. Larger prey is no exception, and they can swallow prey that is more than half their length like a snake. In addition, the jnuckle shark is also a small number of sharks with bare body lateral lines, and there are pressure receptors that can feel changes in water flow on the body side line, and direct contact with water can improve its sensitivity to the surrounding environment.

<h1 class= "pgc-h-arrow-right" > European-style barramundi - deep-sea "goblin"</h1>

Image source: fishesofaustralia.net.au

Another great deep-sea wonder is the European-style barramundi (Mitsukurina owstoni), commonly known as the Goblin shark, which is known for its strange appearance. They are living fossils that have existed for about 125 million years and are the only extant species in the family Mitsukurinidae. The "goblin shark" can be said to be very graphic, and their kisses stretch forward exaggeratedly to form a sharp protrusion, like the nose of a goblin goblin. The upper and lower jaws located under the snout are bird-beaked, and when approaching the prey, they will suddenly pop out like a spring, swallowing the prey in one bite.

Image source: gifjia.com

Such an exaggerated opening action requires two pairs of elastic ligament structures to connect the upper and lower jaws, and while the jaw is ejected, the tongue-like structure will rapidly expand the mouth and suck the prey along with the seawater, and immediately return to its original form. Looking at this picture, the human whose jaw dropped could only close it with his own hand.

<h1 class= "pgc-h-arrow-right" > the current situation of shark survival</h1>

After watching this issue, did you find that the sharks have very different personalities, and even a little cute? In fact, they are not the "killing maniacs" often portrayed in film and television works, even the great white sharks, which are considered the most dangerous, will first issue warning signals when they are offended by their approach, but we humans are their biggest threat (friendly reminder: we who are not professionally trained should not risk disturbing sharks).

Great white shark with divers. Image source: Network

As early as 400 million years ago, the earliest sharks have appeared. Since then, sharks have experienced at least 4 mass extinction events: each time a devastating effect on marine life, but the shark has survived each time with its extremely adaptable ability. However, sharks that have escaped natural disasters have encountered the most severe existential crisis in history when facing man-made disasters. In order to meet the huge demand for shark fin and shark meat, between 1992 and 2000, the once-thriving pelagic whitetip shark population plummeted by 70%, from no danger to vulnerable. According to statistics, the number of sharks reduced in the ocean is as high as 100 million every year. Since the 1970s, shark populations have fallen by nearly half in the northwestern Atlantic Ocean. Nearly a third of shark species are currently endangered.

Shark fin soup as dense as a fish scale. Image source: mission-blue.org

In fact, the value of shark fin soup is more of a product of commercial hype, not only does not match its price of high nutritional value, but even studies have shown that it contains a high concentration of neurotoxin BMAA (β-N-methylamino-L-alanine), which may cause neurodegenerative diseases such as Alzheimer's disease. Not only the fins, but also other parts of the shark's body at the top of the food chain have also accumulated various toxins that are transmitted from the bottom up of the food chain but cannot be broken down.

A shark that sinks into the sea after losing its shark fin. Image source: WWF

Sharks play a vital role in marine ecosystems and, if extinct, are likely to bring unimaginable ecological disasters. Whether it's for sharks, the ocean or humans themselves, it's imperative to protect sharks.

"Sharks are so cute, why eat sharks?" Is the snack not tasty or is the happy water not drinkable? ”

Resources:

All Things January 2019 issue "Shark Surprise"

BBC Documentary Shark

BBC Documentary Whale Shark

https://shark-references.com/species/view/Apristurus-sibogae

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

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

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

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

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

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

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

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

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

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

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

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

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

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

https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/isurus-oxyrinchus/

https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/carcharhinus-leucas/

https://www.floridamuseum.ufl.edu/discover-fish/species-profiles/hemiscyllium-ocellatum/

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

http://www.bbc.com/earth/story/20150611-sharks-epic-migration-revealed

http://www.bbc.com/earth/story/20150519-the-shark-that-glows-in-the-dark

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

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

http://www.bbc.com/earth/story/20150505-the-surprising-world-of-sharks

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

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

https://planetsharkdivers.com/grey-reef-shark/

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

https://www.livescience.com/13173-shark-navigation-target-magnetic-travel.html

https://owlcation.com/stem/Biofluorescence-Colored-Light-Emission-by-Marine-Animals

Mondo, K. et al. (2012) ‘Cyanobacterial neurotoxin β-N-methylamino-L-alanine (BMAA) in Shark Fwins’, Marine Drugs, 10(2), pp. 509–520. doi: 10.3390/md10020509.