Sharks become more aggressive

Why do sharks attack humans?

Sharks don't like people as a meal. Even so, up to 100 are attacked each year. Why? So far, scientists have only had guesses.

Theory 1: The shark confuses its prey and thinks surfers on boards are rowing seals, its favorite food. This is supported by the fact that a shark usually leaves people quickly after the first bite. On the other hand, because of their super senses, sharks should long ago notice who is swimming before they attack. Maybe they are just curious and just try a bite.

Theory 2: A swimmer or diver unconsciously provokes a shark. In fact, if you get too close, sharks threaten them with gestures. Like the gray reef shark: it shakes its head and tail to simulate an attack, sets its pectoral fins upright, humps, and then swims in a spiral or several figures of eight. Bad luck for those who swim on the water and do not see the dance.

Theory 3: The shark is only defending its territory.

Garbage chutes and vacuum cleaners: what sharks really eat

Whale sharks, basking sharks and basking mouth sharks Despite their enormous size, they prefer tiny crabs, which they filter out of the water with the help of special gills. A basking shark can filter around nine tons of water per hour.

The tiger shark is the garbage chute among the sharks. From boots to tin cans, you've found everything in your stomach. He gets them small because he has saw teeth that can even split the thick shell of sea turtles. Well got it.

Others like thatNurse or angel sharks hide in sandy soils and lie in wait for their victims to simply “suck them in”.

AndGreat white sharks prefer to hunt fast seals. They are first killed and then eaten.

Each shark specializes in a different way of hunting or eating. In this way around 500 species could emerge that (almost) do not get in each other's way when hunting underwater.

Sharks only eat every four to seven days. In between they digest. This works because your intestines are folded like an accordion. It prevents indigestible parts of the prey from slipping through. Instead of excreting them, the shark chokes them up again when they are hungry.

All in all, every shark eats around ten times its body weight each year. We humans only about twice as much.

More than skin and cartilage

Most fish have a skeleton made of bones. That of the shark is made of cartilage - like our auricle. This has advantages: cartilage is tough and elastic - it can be bent and twisted without breaking. Cartilage is also lighter. That's why sharks hardly weigh anything in the water and save so much energy for hunting.

Sharks do not have scales like other fish, but a three-layered skin like us humans. It's as rough as sandpaper. Because so-called “placoids” sit on the outside. They are the same shape as shark teeth and are also made of tooth enamel. They let water through and ensure that it envelops the body like a thin film. The placoids act like silencers. This allows the shark to stalk its prey silently. Sharks can taste with their skin too. This is why they often graze on their victims before biting.

Sharks can also perceive electrical fields in the water that other living things create through their movement - for miles. Small antennae, so-called Lorenzini ampoules, sit under their scalp. This is how sharks track down every victim. Because every animal and every person sends out at least one electrical signal - its heartbeat!

And the ampoules can do even more: for example, feel the temperature and thus find hunting grounds again. And maybe even perceive the earth's magnetic field like a compass.