Would it not be wonderful if people who lost an arm or a leg or even a finger in an accident could simply grow another one in its place? But this does not happen in case of human beings. However, you will be surprised to know that there is some living beings in which a new limb develops at the same point from where the original limb has been lost. Development of a new body part in place of a lost one is known as regeneration.
Starfish
If one arm of a starfish is cut off or destroyed, it is regenerated. Hydra, lizards, sponges, newts and earth worms also possess this capability of regeneration. If the tail of a lizard is cut, a new tale develops there.
The ability of regeneration varies in different creatures. Living beings with complicated structures have lesser ability of regeneration. Man and other mammals have a complex constitution. That is why they have lesser ability of regeneration. Mammals can replace hair, nails and skin. They can also repair broken bones and other damaged tissues. In some species, new tissues grow from the surface of the wound replacing the damaged tissues. Sometimes, the tissues that an organism regenerates are different form the original ones. The regenerated structure may be smaller and weaker than the original one.
