The black shark, the dalatia, the American straight-mouthed shark – that’s all it is, like an ordinary one, not huge, but having a couple of very interesting differences from other species. The first is its appearance, and the second is the ability to become invisible, such a “ghost fish”, manipulating light, a lone predator, fast, strong, sometimes suddenly attacking animals larger than itself and able to masterfully hide.
This is a species from the Dalatiev family, the only one of the genus of upright sharks. Brazilian glowing sharks are considered to be its closest relative, similar to them in appearance, structure of teeth and skeleton. They have lived on the planet since ancient times, paleontologists found its fossilized remains in Eocene, Pliocene and Cretaceous soil deposits, more than 400 million years old.
The name of the genus is translated from ancient Greek as “torch”, “flaming brand”, which is associated with their appearance and features. The average length of individuals is 1-1.5 meters, the color is from light gray to black, brown, sometimes purple with black spots. Not very large, but ugly, even among sharks. They have neutral buoyancy due to the large developed liver and high fat content in it.
With a fairly long and flexible body, she has a short, blunt muzzle, with unnaturally huge ugly eyes and thick lips that lack the function of suction, they can only bite and tear. At the same time, her teeth are completely different in shape and size: at the top they are long and narrow, like stilettos arranged in several rows, and at the bottom they are triangular and wide, serrated, like those of other sharks.
But it is not their appearance that makes them special – they have special organs, photophores, with the help of which they absorb and accumulate sunlight in the body. As a result of this, they can not only glow with the help of bioluminescence, but also control this process, sometimes becoming invisible, sometimes illuminating themselves from the inside. Due to their ability, dalatii can hide from enemies and attack suddenly, attract prey or a mate during the breeding season.
This species lives almost throughout the World Ocean, in warm and tropical waters, off the coast of Japan, Australia, South Africa, New Zealand, the British, Hawaiian, Azores, Madeira, Brazil, Java, Mozambique, in the North and South Atlantic. They were not seen only in the north of the Indian and eastern Pacific oceans. Moreover, its individual populations practically do not intersect with each other.
Sometimes they were met and caught at great depths, more than 1800 m, and almost at the surface of the water, but these are isolated cases. Basically, they live near the bottom, where there is an opportunity to hide, at a depth of 200 to 600 meters. Due to the fact that they are rare on the surface, they are considered not as dangerous to humans as other species, but still there were attacks.
Black sharks feed mainly on bony fish species, as well as small sharks, rays, crustaceans, mollusks and worms. Due to the fact that they can hide and suddenly attack, they sometimes swim up and bite out large pieces of meat from larger animals, sharks and cetaceans. In addition, there were cases when dalatians fed on carrion.
Black sharks, like other representatives of this species, are solitary predators, unaware of fear, with a “bad” character, showing aggression not only towards animals of other species and humans, but also towards their own kind. Moreover, they attack not only small and weak animals, no, they suddenly swim up to larger and more dangerous individuals, bite into their flesh, tear out pieces and swim away
As a rule, black sharks, like other representatives of this animal species, cannot exist in groups, their social ties have not been studied and have not been observed by scientists. Basically, they live and hunt alone, mating only for procreation, but sometimes, rarely, fishermen and scientists met small groups of several individuals, but it is not known what this is connected with.
This species is ovoviviparous, that is, the female lays eggs inside herself, where they develop, leave the egg shell in the mother’s body and after that are born. Pregnancy lasts about 2 years, and 10-15 sharks are born at the same time, no more than 30 cm in size. Interestingly, the larger the female, the more cubs she has in the litter. About 12 months pass between pregnancies and the process does not depend on the season.
The natural enemies of dalatia are large fish, mainly sharks, of the same or other species, and sperm whales. But, due to the fact that black sharks are able to disguise themselves, they are practically invisible from the bottom, they are indistinguishable in the water column, they often remain invulnerable to their enemies. Man is more dangerous for them than natural enemies.
Black sharks are the subject of commercial industrial fisheries. Their large liver is very rich in fat, medicines and nutritional supplements are made from it, meat is used for food, bags, wallets, shoes and other things are made from durable leather, which is highly valued because of its dark color. The commercial fishing of black sharks is especially developed in Japan and Portugal.
In the 90s, the population of the species began to decline due to its overfishing, as well as the low reproductive rate of the breed, so the International Union for Conservation of Nature took them under its protection , evaluating their conservation status as “near vulnerable”, requiring catch and population control. In total, this list contains about 4,000 animals that may disappear in the future if man does not stop destroying them.
Sharks are the most incredible creations of nature that have existed for millions of years and have not been fully studied by man. Nature constantly amazes us with the variety of forms of living beings, and the black shark is another confirmation of this. Her ability to control and manipulate the light of her body, combine the glow with invisibility, has yet to be well studied and used by mankind