Fitting one place very well
Why Does Every Animal Live Somewhere Different?
A polar bear would die in a desert and a camel would die on the ice. Being superb somewhere means being hopeless elsewhere.
-
Step 1 of 5
A habitat is a set of problems.
Every place asks the same questions in different ways: how to stay the right temperature, find water, find food and not be eaten. The answers only work locally.
-
Step 2 of 5
Being good at one thing costs another.
Thick fur is wonderful on ice and fatal in a desert. Every feature that solves one place's problem well makes another place's problem worse.
-
Step 3 of 5
So animals specialise.
Rather than being adequate everywhere, animals get very good at one place. Competition pushes them into it: whoever fits a place best keeps it.
-
Step 4 of 5
Layers within one place count too.
A single forest holds several habitats stacked up. Animals in the canopy, the trunks and the leaf litter live metres apart and never really meet.
-
Step 5 of 5
Which is why losing a habitat matters.
An animal built for one place cannot simply move. Clear the forest and the animals that fit it have nowhere to go that they are any good at.
Some animals go the other way and specialise in change itself. Rats, pigeons and foxes fit almost anywhere, which is why cities are full of them.
The short version
Each animal is shaped by the problems of one place, and being superb there is exactly what makes it useless elsewhere.
Try it yourself
Look at what lives under a log, on the log, and in the tree above it. Three habitats within arm's reach.