Stop Shark Attacks With Vomit!
The hagfish has developed a slimy substance that it uses to defend itself against sharks and other predators. The slime blocks the gills, making sharks cough and struggle to breathe.
The hagfish belongs to a group of animals that biologists consider the most primitive among vertebrates. But when they must protect themselves against enemies, they turn out to be rather sophisticated.
The hagfish releases a slimy substance that makes larger predatory fish gasp for breath. The slime swiftly blocks the predatory fish’s gills, so it cannot absorb oxygen. When a hungry shark dares to enter its teeth into a hagfish, it will hence very quickly let go of its prey again, allowing the hagfish to escape unharmed.
Biologists from three US universities have studied the scenario via several video recordings and were inspired to take a closer look at the skin of the hagfish to find out how it can escape the attacks so easily. The scientists assumed that the skin was very sturdy and hence difficult to penetrate for the teeth of the predatory fish. So, they tested the breaking strength of hagfish skin, comparing it to the skin of 21 other fish species. However, the study showed that hagfish skin is not any sturdier than that of other species. When the hagfish escapes predator fish teeth almost unharmed, it is instead due to the fact that the skin is very loose.
Not only the scientists’ video recordings, but also other observations demonstrate the efficiency of hagfish defence mechanisms. When biologists study the stomach contents of other large predatory fish, they very rarely come across hagfish remains.