Like other sharks, the cookiecutter's entire skeleton is made of cartilage. The shark does not have a single bone in its body. Even its teeth are cartilage, covered with a very hard material. The teeth of the upper and lower jaws are different. The upper teeth are narrow spikes. The lower teeth are larger and extremely sharp. They overlap to form a saw-like structure. This structure is so sharp that it is difficult for people to catch cookiecutters. The sharks can quickly chew their way through a net and escape. A cookiecutter's teeth are not permanent. They constantly fall out and are replaced by new teeth. Sometimes an entire row of teeth is lost at once. The cookiecutter shark may swallow its own teeth if they fall out while it is eating.