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.
African Spiny Mouse
The African Spiny Mouse is able to release its skin tissue when attacked, and then completely repair it. It also has the ability to heal holes in its ears. It quickly closes holes with new skin, regenerates hairs, fat cells and cartilage, without scar tissue. Like salamanders and lizards, when a tail is lost, these mice grow a new one.
Starfish, sea star
The starfish is an echinoderm, a cousin to the spiny sea urchin, sand dollar and sea cucumber. These five-limbed creatures have the ability to regenerate their arms and sometimes, their whole bodies. When a starfish is down to one arm, as long as it has its central nerve ring intact, it can grow into an entirely new five-legged starfish.
Sea cucumbers are echinoderms, like starfish and sea urchins. Sea cucumbers are ocean dwellers, though some inhabit the shallows and others live in the deep ocean, on or near the ocean floor, sometimes partially buried beneath it. Seasonally, or when threatened, sea cucumbers will contract their muscles and jettison some of their internal organs out of their anus. The missing body parts are quickly regenerated, sometimes in a week.
Sources: National Geographic, Journal of Anatomy, Scientific American