The piranhas scattered in the Amazon River are a frightening animal that hunts in swarms and can chew animals and humans into skeletons in a short period of time.
Piranha with teeth exposed
However, there is a big fish in South America that is not afraid of piranhas, not only is it not afraid, but they feed on piranhas. What is so powerful as a big fish? How is it "ferocious" enough to feed on piranhas? Does it have any weaknesses?
This large fish, which can easily prey on piranhas, is called arapaima, also known as walrus fish. This fish is biologically classified into the genus Of Rayfin Fish, Bony Tongue Fish, and Arapaima macrophylla.
Arapaima
(1) Huge living fossils
Arapaima is a well-deserved living fossil that has existed as early as 100 million years ago, and it still retains many characteristics of early aquatic life. Its most prominent feature is its stunning body shape. Although arapaima is also a freshwater fish, it is surprisingly large compared to other freshwater fish. Arapaima is one of the largest freshwater fish on Earth, with a body length of more than 2.5 meters. The longest arapaima is three meters long!
In addition to its astonishing body length, the weight of the arapaima is also amazing. Arapaima easily weighs more than 100 kilograms, and the heaviest is even 200 kilograms. Compared to small freshwater fish of only a few dozen grams, arapaima is really a behemoth. Arapaima is so heavy that it usually takes two to four adults to lift an adult arapaima completely.
Catch arapaima
The huge size can be said to be an iconic feature of paleontology, many creatures have gradually evolved small size due to the need for survival, while arapaima still maintains the huge size of paleontological characteristics.
(2) Unique body structure
The arapaima is very unique in its body structure, the most prominent of which is its sharp "teeth". Like most freshwater fish, arapaima have small, thin teeth. But it does not rely primarily on small teeth to prey on predators, surprisingly using the tongue, which is supposed to be an organ of taste. In human common sense, the tongue of any animal is made up of softer muscle tissue. The tongue of the arapaima is a hard bone, covered with strong and sharp "teeth", and its name "giant tongue" is hence the name.
Creatures living in extreme environments have evolved unique life-saving skills, and Arapaima is no exception. Although the Amazon forest is rich in annual rainfall, the amount of dissolved oxygen in the rivers often declines. Any aquatic animal that wants to survive in a low oxygen-content environment must evolve methods that do not breathe air through water, and the African lungfish that do the best job of this is the African lungfish.
African lungfish
Although the arapaima did not evolve lunges like the lungfish, it has a swim bladder that can breathe air directly. In this way, the arapaima can still survive during the dry period, and when the living water re-flows into the river, it will be replaced by gills to breathe.
(3) Attack high and defend high "tanks"
The most amazing thing about the arapaima is its unique attack (feeding) method. Arapaima is a typical carnivorous fish that preys on aquatic animals mostly distributed in the Amazon River, and even ferocious piranhas cannot escape its predation. When the Arapaima is preying, it opens its large mouth and inhales vigorously. Like a vacuum cleaner, it sucks the prey into the mouth with a huge suction force and kills it with a hard tongue. The killed prey enters the digestive organs directly through the esophagus for digestion.
To be able to prey on ferocious piranhas, arapaima must be protected by a hard shell. The arapaima shell is so hard that the piranha's fangs can't bite at all, and even a kitchen knife that can easily scrape off the scales of other freshwater fish can't help it. Therefore, only the sharp end of the horn hammer can be used to knock off the scales of the arapaima bit by bit.
Handle the scales
The shell structure of the arapaima is very interesting, and the outermost layer is the unusually strong fish scales. The scales of most fish are as small and transparent as plastic sheets, and the scales of arapaima are thick and large scales. The scales of arapaima are unusually strong, and the indigenous people of South America will polish the scales of the arapaima to make daggers. The inner layer of the scales of the arapaima is rich in elasticity and soft skin. It clings to the fish scales and controls the state of the protective armor by adjusting the opening and closing of the fish scales by elastically adjusting them. In this way, other large carnivores can't do anything with the sturdy shell of the arapaima.
The strong outer armor of the arapaima has also aroused the interest of scientists, and the most interested in this structure is the relevant researchers who develop new body armor. The advent of body armor did save the lives of most soldiers, but the current body armor has many flaws, such as not being able to protect the limbs, being too bulky and so on. Under the premise of reducing its own weight, providing better protection capabilities is the main research direction of the new body armor.
Vest
The shell of the arapaima is protected by only one layer of fish scales, but the sharp object can hardly penetrate, which is closely related to the material and arrangement of the fish scales. Robert Ritchie, a materials scientist at the University of California, Berkeley, considers arapaima scales to be "the hardest and most flexible biological material," a conclusion he concluded after his team rigorously tested arapaima scales. They underwent stress tests and electron microscopy analysis of arapaima scales, and carefully analyzed the impact resistance principle of arapaima scales.
Originally, the outermost layer of the arapaima scales was a hard calcareous layer, and the inner layer was soft and tough collagen fibers. The reason why the fish scales are not completely composed of a hard calcium layer is because this will turn the fish scales into a glass-like substance, and the ability to resist blows will be weakened.
Arapaima scale structure
Although the secret of arapaima resistance has been discovered, there is still a long way to go to develop new body armor modeled on this principle. In the way of development is the material issue, as there is currently no composite material that can seamlessly transition from tough to hard. Robert Ritchie remains optimistic about this issue, believing that future 3D printing technology could make it possible to mass-produce this new type of composite material.
Although arapaima is the dominant in South America with its strong defensive ability and ferocious predatory ability. But it has a fatal weakness – character laziness, and this weakness also allows it to be preyed upon by humans. When not eating, arapaima is not to provoke other fish "Mr. Good", other large carnivores because of jealousy of the hard shell of arapaima, but also rarely hit its ideas, hunting it only people who value it infinitely.
Catch arapaima
For the less affluent South Americans, the arapaima is a cash cow gifted by nature. Arapaima is unique in appearance, and some individuals with beautiful scales are even caught and raised as ornamental fish. As I mentioned earlier, the indigenous people of South America would make daggers from the scales of arapaima, and after entering the twenty-first century, there are still people who retain this local handicraft. They would process the scales of arapaima into daggers or other crafts and sell them to tourists.
Arapaima scales
The biggest use of hunting arapaima is actually food. Arapaima is so heavy that it can naturally shave off a lot of fish from the skeleton. Killing a tongue fish can get almost 70 kilograms of fish meat, enough for a family to eat for a long time. In order to preserve the endless fish, the South Americans would salt the caught arapaima or dried it. These by-products of arapaima have also become unique local specialties of South America.
Of course, there is still a certain danger in catching arapaima. This is because arapaima, although docile, will frantically slap the fisherman with its tail when it is caught alive. The arapaima tail is so strong that it can easily break ribs and cause internal organ injuries. In order to ensure safety, the South Americans directly killed the arapaima with a stick, then used a hammer to knock off the scales of the arapaima, and finally shaved off the flesh.
Processed arapaima
Although the arapaima has succeeded in dominating the rivers of South America with its hard scales. However, because of its lazy nature, it was hunted down by humans, and the number was greatly reduced. There are still many exotic species like Arapaima on Earth, and they have inspired human invention to varying degrees. But it is also on the verge of extinction because of human activities.
Animals not only play an important role in the ecosystem, but also the best "teachers" for humans. Therefore, the protection of wild animals is very necessary, and protecting them is also protecting human beings themselves.