None of the existing shark species resembles its ancient ancestors as much as the sixgill shark. Brave divers try to ride a clumsy and harmless sixgill shark when they meet unexpectedly. The sea creature impresses with its size. A chance meeting with him in the water column excites the imagination, like meeting with a dinosaur.
Origin of the species and description
Sixgill Shark — the largest in size species from the family of polygills, a genus of cartilaginous fish. Scientists have identified 8 species of sixgill sharks, but only two of them today plow the world's oceans, and the rest have long died out.
- blunt-headed tingill or gray sixgill shark;
- Bigeye sixgill shark.
The polygill order is considered the most primitive and one of the most ancient.
Video: Sixgill shark
Like all representatives of the genus of cartilaginous fish, sixgills have a number of their own features:
- they lack a swim bladder;
- fins are horizontal;
- their body is covered with placoid scales;
- the skull is completely cartilaginous.
The buoyancy of the sixgill helps to maintain a greatly enlarged liver with a high fat content. In addition, in order not to drown, sharks constantly move in the water column, supporting their massive body with the help of fins. The most ancient remains of these creatures were found in sediments that date back to the Permian period, the beginning of the Jurassic. To date, 33 species of polygill sharks are considered extinct.
Interesting fact: Due to the slowness and large size, representatives of this species are often called cow sharks. They are fished but not of great value.
Appearance and Features
The size of individual specimens of the gray sixgill shark can exceed 5 meters and weigh more than 400 kilograms. The big-eyed subspecies is somewhat smaller. Depending on the characteristics of the habitat, the color of the body of a shark can be different: from light gray to dark brown.
All individuals have a light belly and a pronounced lateral line along the entire body. One dorsal fin is strongly displaced towards the caudal fin, the stalk of which is very short, and the upper lobe is large and has a characteristic notch. There are six gill slits on both sides of the body in front of the pectoral fins.
The body itself is elongated, rather narrow, spindle-shaped. The snout is short and blunt. At the top of the wide head is a round hole — sprinkler. The oval-shaped eyes are located immediately behind the nostrils and lack the nictitating membrane.
The mouth of a shark is medium in size with six rows of comb-shaped teeth that are of different shapes:
- the upper jaw is studded with triangular teeth;
- they are comb-shaped on the lower jaw.
Thanks to this feature, the shark is able to capture various prey, including very slippery ones.
Interesting fact: This type of shark spends most of the day at great depths, rising to the surface only at night. Because of this lifestyle feature, their eyes have the ability to fluorescent glow. This ability is considered very rare among sharks.
Where does the sixgill shark live?
Sixgill can be found in the depths of the Atlantic Ocean. It lives in the waters along the Pacific coast of America: from sunny California all the way to northern Vancouver. A sufficient number of individuals live off the coast of Australia, South Africa, Chile, near the islands of Japan.
Sixgill sharks are typically found at depths of around 100 meters, but have been known to dive 2,000 meters or more with ease. The pressure at such depths can exceed 400,000 kg per square meter. During the day, these creatures move slowly in the water column, prowling along the bottom in search of carrion, and closer to the night they rise closer to the surface to hunt fish. Just before dawn, the prehistoric giants return to the depths again. Off the coast of Canada, sixgills are found near the surface of the water even during the day, but this can be called a rare exception.
Interesting fact: The sixgill blunt shark is of commercial importance. It is in special demand in California, some European countries. She is usually dried.
In Germany, the meat of this shark is known to be used as an effective laxative. The liver of the sea giant is not eaten, as it is considered poisonous due to the high content of toxins.
What does the sixgill shark eat?
Typical Diet prehistoric giants:
- various medium-sized fish, such as flounder, hake, herring;
- crustaceans, rays.
There are cases when this species of sharks attacked seals and other marine animals. Sixgills do not disdain carrion, they can take prey from their relative or even attack him, especially if the individual is weak due to wounds or is smaller.
Due to the special structure of the jaws and the shape of the teeth, these creatures are able to eat varied food. They easily deal with even large crustaceans. If a predator grabbed the prey with its powerful jaws, then it no longer has a chance of salvation. The shark begins to shake its head from side to side and rotate its body, causing maximum damage to its prey. Only outwardly they look clumsy, but during the hunt they are capable of lightning attacks.
Despite their large size and intimidating appearance, shark cows are not considered dangerous to humans. Over the entire history of observing them, several cases of attacks on people have been recorded, but in each of them the shark was provoked by the incorrect behavior of divers. When meeting with a person at depth, these creatures show great curiosity towards him and underwater equipment. They can circle around for a while, but with obsessive attempts at contact they quickly swim away.
Character and lifestyle features
It is very difficult to observe sixgills in their natural habitat, as they prefer to swim at great depths. Like other deep-sea inhabitants of the seas and oceans, their way of life has long remained a mystery to humans. It is not advisable to specially raise sixgill sharks to the surface, as they immediately become disoriented and behave atypically. It is for this reason that biologists have abandoned this method of study.
Scientists have found a different approach to these giants — special sensors began to be attached to the body of sixgills. The device helps track the migration of deep-sea inhabitants, provides additional information about the state of the body and changes in it. This method is also not considered easy, since you must first go deep underwater and find the sixgill shark.
These creatures are known to be loners. They are characterized by daily migrations in the water column. Cases of cannibalism have been observed, when healthy adults attacked sick relatives or those who accidentally became entangled in fishing nets. The larger-eyed sixgill shark, which is smaller, is less common than the gray blunt-nosed sixgill shark. For this reason, its lifestyle and reproduction features are practically not studied.
Social structure and reproduction
The sixgill giants are ovoviviparous. During the season, the female is able to give birth to an average of 50-60 sharks, but there are cases when their number reached one hundred or more. It is noted that the survival rate of young animals is 90 percent, which is a very high indicator. Frilled sharks are known to produce between 4 and 10 pups and have only a 60 percent survival rate.
Individuals reach sexual maturity when their length is more than two meters. After fertilization, the eggs continue their development inside the female's body in a special brood chamber, receiving the necessary nutrition from the yolk sac. It is very difficult to track the further fate of the young, so biologists do not know the exact process of development of sharks. There is an assumption that at first, young individuals stay closer to the surface of the water, where hunting is most effective. As they grow older, they descend to greater depths. Young animals gain weight quite quickly.
Interesting fact: At the bottom of the Mediterranean Sea at great depths, numerous pits are often found, which can reach 2-3 meters in depth. Biologists believe that these are traces of sixgill sharks hunting giant crustaceans.
Natural enemies of sixgill sharks
Despite their impressive size and dangerous jaws, even these prehistoric giants have their enemies. They can become a victim of a flock of killer whales, which are distinguished not only by their great strength and sharp teeth, but also by their special ingenuity. Killer whales are able to attack from several sides at once with the whole flock.
Adult individuals rarely become their prey, more often they attack young animals. Killer whales are able to surprise and dodge the dangerous jaws of the sluggish sixgill. Due to the fact that sharks rise to the surface only at night for a few hours, meetings between these two predators are not very common.
An ordinary hedgehog fish can be dangerous for a powerful giant. Since hungry sharks can grab almost anything, sometimes their prey is prickly fish, swollen to the shape of a ball. The spines of this creature severely injure the shark. The predator can die from starvation or severe infection.
Human activities also affect the well-being of prehistoric fish. There are cases when deep-sea inhabitants swallowed garbage, which floats in abundance throughout the world's oceans. As the seas become polluted, the number of crustaceans, some species of fish, which are the usual diet of sixgills, decreases.
Population and species status
Despite the fact that sixgills are distinguished by their special survival and fertility, a small number of enemies in their natural habitat, their numbers are constantly fluctuating, they are especially sensitive to overfishing. View Status — imminent threat or in the near future there is a danger of extinction. Nevertheless, the shark is still an object of trade and sport fishing in a number of countries, including European ones. The exact number of these creatures cannot be established due to the peculiarities of their secretive lifestyle.
An interesting fact: In some states of America, the meat of underwater giants is smoked, in Italy they prepare a special delicacy for the European market. In addition, the meat of sixgill sharks is salted, frozen, dried, used in the production of fishmeal and feed for many domestic animals.
Strict control over trapping. When overfished, their numbers are restored for a rather long time, since only individuals whose body size has exceeded 2 meters are capable of procreation. It is also necessary to monitor the level of pollution of the world's oceans. Being the main deep-sea predator, the sixgill shark is increasingly left without its usual diet and is forced to be content exclusively with carrion.
The sixgill shark has been living in the waters of the oceans since the time of the dinosaurs and has come down to our times almost unchanged. It is only known that millions of years ago their size was even more impressive. Meeting them in their natural habitat — this is a great success for a diver, which will undoubtedly be remembered for a lifetime.