Wouldn't it be amazing if a person who lost a limb could simply grow it back? It happens all the time in the animal kingdom. Sea Cucumbers, for instance, don't need to die when they lose internal organs. They simply grow new ones in a process called regeneration. We use regeneration to grow new toenails and small parts of our liver and brain. But why can't we regrow other important body parts, like legs or lungs? Scientists are studying an array of animals and insects in order to understand regeneration and how it can further help us.
Because of how violently sharks eat, sharks break and lose teeth all the time. But you don't have to worry about being gummed to death. Sharks lose as many as 30,000 teeth over their lifetime and regenerate new teeth in as little as a week. The new teeth rotate forward from a groove located behind the front row of teeth.
One of the most popular animals for scientists to study, the axolotl salamander, regenerates missing limbs, its tail and parts of its brain, heart and lower jaw. Mexican axolotls can recover leg functions after being paralyzed. They make new connections and neurons that allow them to use their legs again.
After a fall and winter of battling and showing off their antlers, deer shed them and regenerate a brand new set before the next autumn. It's one of nature's most amazing examples of regeneration. The average deer's antlers weigh between 59 and 66 pounds.