Research

Why do fish rub against the bodies of dangerous sharks?

At the moment, scientists know that in the seas andthe oceans of our planet are home to about 250,000 species of animals. Their number increases every year, because with each dive into deep waters, scientists make new discoveries. In the aquatic environment, fish and other relatively defenseless creatures have to live next to dangerous predators like sharks. Recently, American scientists made observations and noticed that some species of fish approach sharks and rub against their bodies. In fact, researchers have been observing such a phenomenon for more than ten years, but no one has seriously looked for the reasons for such behavior in fish before. They sometimes rub against hard rocks to get rid of adhering parasites or to renew their scaly cover. But why do they rub against the bodies of predators who can easily eat them?

Dangerous shark surrounded by small fish

Friendship between fish and sharks

The results of the scientific work carried out werepublished in the scientific journal Ecology. As part of the study, scientists from the US state of Florida studied underwater photographs and videos of fish and sharks. They managed to notice 47 cases of fish rubbing against shark bodies. This happened in 13 regions of the World Ocean: 12 species of fish rubbed against the bodies of 8 different sharks alone or in groups of up to 100 individuals. They clung to predators for 8 seconds to 5 minutes. At the same time, the fish were not afraid to swim even to the great white sharks, which are considered the most dangerous.

Fish rub against sharks for about 5 minutes

Scientists tend to assume that due to friction aboutbodies of sharks, fish get rid of parasites - I noted above that they do the same by rubbing against rocks. Also, rubbing against sharks can help them get rid of old scales, which helps the growth of new outer cover.

Sometimes even aquarium fish rub against the rocks.

Shark scales features

But why fish as a "brush" sometimesusing dangerous sharks instead of safe rocks? Researchers believe that fish are very attracted to shark scales. Unlike the outer cover of other inhabitants of the seas and oceans, shark scales are shaped like teeth. There is even a term dermal denticles specifically to describe such scales. Their structure is indeed more like the structure of teeth than scales. So, in the center of the shark outer cover particles there is pulp - fibrous connective tissue that is penetrated by blood vessels. The pulp is covered with a layer dentin, the hard tissue found in the teeth of all mammals. The outer layer of shark scales consists of vitrodentinwhich is identical to the enamel of human teeth.

Scales of different types of sharks

Sharks need a rough surface of the body in order toso that there is not a lot of noise while sailing. Tiny particles create small vortices that make sharks invisible as they move. And this, as you could already understand, significantly increases the chances of catching prey. Also, the body covered with small teeth is able to protect sharks from serious injuries. After all, these dangerous predators also have enemies - for example, killer whales, which I talked about in more detail in this article. Even the sharp teeth of these creatures cannot bite through the 10-centimeter skin of sharks. In addition, the surface of their body itself can cause serious injury.

The main enemies of sharks are killer whales

See also: What caused the extinction of 90% of the sharks living on Earth millions of years ago?

How do animals help each other?

Scientists have noticed many times that sharkseven fish come, on which predators are actively hunting. But at the same time, in most cases, sharks do not pay attention to sudden fellow travelers. Most likely, fish know how to assess risks in some way and swim to predators when they are calm and do not pose a great danger. It can also be assumed that by their friction, fish also benefit sharks, only at the moment scientists cannot say which one. Some fish do a great service to aquatic predators. For example, pilot fish (Naucrates ductor) feed on external shark parasites. Those are only grateful for this and not only allow them to swim next to them, but also allow the fry of fish to pinch the remnants of food between their teeth.

Pilot fish next to a shark

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Finally, let me remind you that recently scientists announced,that in fact most sharks do not harbor any aggression towards humans. Researchers have suggested that predators are simply studying humans and that the most affordable way to do this is to take a few bites. The version is interesting, but it does not turn sharks into harmless good people. From time to time they attack people and inflict serious injuries. On our site you can find out about the "smartest" way to rescue after a shark attack.