Living or non-living?

Avadhi and Aayush go for a morning walk with their parents. Avadhi sees some shells and tries to pick them up. Her mother stops her: a shell could be the home of a living snail, and it is actually part of the snail's body. How can something that is not even moving be part of a living being? In school, their teacher starts a discussion: what makes something living?

Movement alone cannot decide it. A car moves on the road, but it is not alive. A cartoon character dances across a screen, but it is not alive either. Compare yourself with a car: you grow, and a car never does. And plants do not move from place to place, yet they are living. So we need more than one characteristic.

The characteristics all living beings share:

• they show movement
• they need food (nutrition)
• they grow
• they respire
• they excrete (remove waste from the body)
• they respond to stimuli
• they reproduce
• and in the end they die.

A thing that does not show these characteristics is non-living.

Reproduction is producing new ones of one's own kind, like puppies and kittens. It is needed for the continuity of life: without it, a kind of living being would one day disappear. A pencil, a chair or a bulb never has young ones.

When a living being can no longer show these characteristics, even though food, air and water are there for it, it is said to be dead.