The monster's self-defense moves make sharks shy

Blind fish have super-liquid skin layers that help it to avoid serious internal damage when bitten by enemies.

The hagfish are exotic animals.(Photo: Science Magazine.)

The hagfish are so strange creatures that live in the deep sea with strange biological characteristics that scientists find it difficult to classify them. For example, this is the most decadent animal with a skull but no backbone, meaning it is impossible to ascertain whether it is a vertebrate fish or a transitional invertebrate, an evolutionary precursor of bone normal life.

can live for months without food and be able to absorb nutrients through the skin through no scales. But one of their most peculiar features is the reaction to release large amounts of mucus when attacked, making them nicknamed "viscous eel".

The hagfish are unharmed before the shark's bite.(Video: YouTube.)

Previously, researchers believed that this mucus and anti-bite skin were a key defense weapon to prevent hagfish from eating meat. But new research shows that other strange properties in the skin may play a more important role. Scientists have found that fish skin hagfish still suffer from open wounds, but possess useful properties that allow animals to avoid serious internal injuries when bitten through the skin.

The skin is somewhat like a very soft sack and only attaches to the hagfish body at two points. This structure makes the skin loose enough to let the foes of the glider only graze the hagfish's body. The attacker will have trouble if he wants to cause serious injury.

" Large looseness combined with minimal contact between the skin and muscles allows their bodies to not be damaged even when the skin is torn, " said Douglas Fudge, associate professor of biology at Chapman University, USA. The main author of the study, said.

Once surviving the first bite, the hagfish releases mucus, which can block the airways of predators. This combined self-defense measure seems to be extremely successful, helping the hagfish survive for 300 million years on Earth and evolve very little during that period. In fact, animals are so good at escaping attacks that they are rarely found in the belly of other fish. Many predators avoid hunting them due to their very low probability of success.

In the study, the scientists conducted an experiment to find out how fish hagfish avoid injury from attacks. They create a spring-loaded shark jaw model and mount teeth to simulate bites (Mako sharks are one of the few hagfish hunters). The scientists then placed the hagfish carcass inside the model teeth and carried out tests to bite the skin.

They found that the teeth were ripping the skin of fish in each test. However, the muscles under the skin are not damaged any time. Because the skin is easier to heal than the internal organs, it is certain that hagfish will survive the attack. The study results were published in Royal Society Interface magazine. Scientists created the experiment after watching a video filming the self-defense mucus hagfish in nature.

Hagfish also have many other strange biological characteristics. They have huge amounts of blood compared to their body size, circulating in the hollow space between the body and the skin. This amount of blood is so high that hagfish have many hearts to pump blood.

Having a large amount of blood underneath the soft skin does not seem too useful for survival purposes, especially for an animal near the end of the food chain. However, their blood is pumped around the body at a pressure almost no higher than the surrounding water, which minimizes blood loss when attacked.

Hagfish can even twist their bodies into knots, a behavior that is supposed to evolve to compensate for the incomplete lower jaw structure, which helps the upper jaw bite food. Hagfish help the ocean ecosystem by digesting and decomposing dead animals into the sea floor, creating a clean environment for other fish.