Distinguishing Features
We see many things around us—shells, snails, cars, and trees. Sometimes it can be confusing to categorize them. For example, a car moves and consumes fuel, but it is not alive. A cloud grows in size, but it is not alive.
To identify something as living, it generally must exhibit all of the following characteristics over its lifespan. If it lacks these intrinsic biological processes, it is considered non-living.
Comparison Table
| Feature | Living Beings (e.g., Pigeon, Plant) | Non-Living Things (e.g., Pencil, Car) |
|---|---|---|
| Growth | Grows from within; irreversible. | Does not grow (or grows by accumulation, like a snowball). |
| Nutrition | Needs food/nutrients to survive. | Does not need food. |
| Respiration | Breathes/respires to release energy. | Does not respire. |
| Reproduction | Produces young ones of its own kind. | Cannot reproduce. |
| Excretion | Removes waste from the body. | Does not excrete. |
| Response | Responds to stimuli (light, touch). | No response to stimuli. |
| Life Span | Has a birth and death. | Exists until destroyed; no biological death. |
Warning
The “Movement” Confusion: Movement alone is not a defining feature of life.
- Animals move from place to place.
- Plants do not move their whole body, but parts of them move (e.g., flowers opening, roots growing down).
- Cars/Clouds move due to external forces or fuel combustion, but they do not grow, reproduce, or respire.
The Case of the Shell
In the introduction, Avadhi finds a shell. A shell itself is non-living (it’s a hard protective layer), but it was once part of a living snail. Once separated or if the snail dies, the shell remains as a non-living object.