I think this fact is amazing. My list only contains this phenomenon. You can call it "single" if you like. This is a form of echolocation, which is very similar to the auditory mechanism of bats. Bats make sounds and interpret the reflected sounds after hitting objects. But the use of this strange sound goes far beyond this.

1839, in the first scientific paper about sperm whales, Thomas Beer, a surgeon on a whaling ship, wrote that sperm whales are "one of the quietest marine animals". He was soaked to the skin.

Sound is mechanical. The knocking sound is a tight eardrum. The louder the sound, the heavier the knock. If the sound is too loud, it will tear your eardrum to pieces, which will bring great inconvenience to your hearing and balance.

You will also feel very uncomfortable. When the shock wave generated by the bomb leveled the house, it was the sound of bricks and glass tearing. Sound can kill you. The click of sperm whales is the loudest sound made by animals on earth. I haven't seen so many excellent answers to a question for a long time, but I still want to add my point of view. Here are some of the most attractive animal defense mechanisms I know.

Hairy frog or wolverine frog, hairy frog is amazing in many ways. First of all, male skin has fine hair-like filaments, which are used to collect oxygen. Secondly, they used the broken toe bone as a weapon. Yes, frogs deliberately break the pointed bones of their toes so that they can stick out as claws. Claws only appear on the hind feet and are usually attached to the joints through collagen. When the wolverine frog is caught or attacked, its collagen will break and its sharp bones will open. This defense mechanism is almost unique in the whole animal kingdom, although frogs are somewhat similar.

Ever wonder why it's called stickleback? This is because the bone blades on both sides of their tails (orange things in the photo) are reminiscent of scalpels. When attacked, tropical fish will bounce these thorns outward and then take them back when the danger is over. As we all know, the surgeon's fish blade can cause deep wounds to people.

Although this fish does not have any form of venom, it is said that cutting it from tropical fish is "extremely painful" and usually penetrates deep. Nausea, muscle pain and anxiety are all consequences of the above injuries.

In the Pleistocene, Jamaica was home to a bird called Archaeopteryx. It is one of the only two flightless birds in history, with plum blossoms on its wings. Its metacarpal bones are so thick that some people think that Archaeopteryx may walk like a quadruped, which makes them a weapon against exotic animals.