(ORDO NEWS) — When imagining the interaction between tuna and shark, we usually imagine a brutal hunt in which the unfortunate tuna is torn in half. However, in some cases, peaceful fish purposefully look for their sworn enemies, because they have a very tough skin that can be scratched.
Imagine yourself in the place of a large yellowfin tuna swimming in the open ocean and suddenly feeling itchy somewhere under the eye.
Perhaps this is just a tiny scratch, or maybe a parasitic crustacean that decided to feast on someone else’s blood.
In any case, pulling it out on your own will not work – there are no hands – so you have to look for an assistant.
Usually, in order to get rid of parasites, fish seek out specific areas where cleaners live , such as wrasses.
However, they are usually found only within coral reefs, and in the middle of the open ocean they are almost impossible to detect.
Therefore, tuna will have to look for another way to relieve the itch. And he really finds it… in the form of a shark.
After reviewing thousands of hours of footage of marine life collected using a system of floating cameras, the researchers found an unexpected interaction between several species of predators and even more species of peaceful fish.
Tunas and other large fish literally chased the sharks and rubbed their sides and head against their scales.
Since the skin of a shark is covered with many small teeth and feels like sandpaper (by the way, in pre-industrial times, people mined it for this very purpose), it is well suited for scratching, getting rid of dead skin and clinging parasites.
At the same time, fish behaved differently with sharks. So, the tuna neatly lined up behind the predator and in turn touched its tail, and the rainbow mackerel literally stuck around, randomly poking at the back of the shark’s body.
Scientists underline how important sharks are to the overall health of marine life: not only are they a necessary element of the marine food chain, but they are also an indispensable comb for those species of fish that spend most of their time in the open ocean.
With shark populations rapidly declining around the world, this could lead to an increase in parasitic infections, and fishermen who get rid of predatory competitors will end up with schools of exhausted, emaciated fish eaten by parasites instead of fish abundance.
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