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 in reality it does not happen so in case of human beings. However, you will be surprised to know that there are 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.

If a small arm of a starfish is cut off or destroyed, it is regenerated. The hydra, lizards, sponges, newts and earthworm also possess this capability of regeneration.

The ability of regeneration is different 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. Mammals can also repair broken bones and other damaged tissues. Regrowing of the wings of birds is another example of regeneration.

In some species new tissues grow from the surface of the wound replacing the lost or damaged tissues. Sometimes, the tissues that an organism regenerates are different from the original ones. The regenerated structure may be smaller and weaker than the original one.