Everyone thinks I'm overdramatic when I'm upset but when

How is that even possible...?

Octopuses can sometimes suffer from autophagy, or self-cannibalism. That is what is described as "eating its own arms." This is caused by stress. A stressed animal is not a healthy animal and is open to infection. It is believed that it is caused by a virus/bacteria which can manage to take hold on a stressed octopus. The biting is said to be due to irritation and biting alleviates the affected area. An octopus can lose an arm without harm and regrow it. By biting it off, the octopus loses the infected arm and hopefully a healthy one regrows, but in captive situations, probably caused by bad water quality, the infection can't be shaken off. The stressed, infected octopus dies with its arms in tatters. Ever seen a dog that constantly licks its paws to the point of bleeding? Again caused by a secondary infection and even after the infection is gone, a dog may keep the habit. Seemingly hurting itself on purpose, but really just responding to a given situation, is called habituation.

That's disgusting