Biology
Animal senses
Bats hear their surroundings, bees see colours we cannot, and birds sense the Earth's magnetic field.
You experience the world with your senses: sight, hearing, smell, taste, and touch. Many animals have completely different senses or perceive far more than we do. They live in a world that would feel strange to us. In this chapter you will discover some of these amazing sensory worlds.
Hearing instead of seeing
Bats hunt at night. They are not blind, but in complete darkness their eyes are of little use. Even so they catch tiny insects. Their trick is called echolocation: the bat sends out calls so high that our ear cannot hear them. Obstacles and prey bounce these calls back, and from the echo the bat hears where something is and how far away it is.
A signal in the body
No matter which sense: it all begins with a stimulus, for example light, sound, or a smell. Sensory cells turn this stimulus into a signal that runs along to the brain. Only in the brain does it become an impression the animal can use. In every animal with a nervous system this follows the same basic principle, in a bat just as in you.
Stimulus 6 over threshold 4: neuron fires
Senses we do not have
Some animals perceive things that stay completely hidden from us. Bees see ultraviolet light and so notice patterns on flowers that are invisible to us. Migrating birds sense the Earth's and use it to find their way over thousands of kilometres. Dogs smell so finely that they follow trails that, for our nose, are not there at all.
Exercises
0 of 6 solvedTime to try it yourself. You can't break anything, every attempt counts.
How does a bat find its prey in complete darkness?
Which organ receives the signal at the end so that an impression forms?
At the start, these human senses are named: sight, hearing, smell, taste, and touch. How many is that?
Put the path of a sensory impression in the right order, from the start to the finished impression.
- 1The signal runs along nerve cells to the brain.
- 2A stimulus like light, sound, or smell arrives.
- 3Sensory cells turn the stimulus into a signal.
- 4In the brain an impression forms that the animal uses.
A sensory impression passes these stations: first the stimulus, then the signal along the nerve cells, and last the brain. How many stations is that?
Match each animal to the special sensory feat named in the text, one that is out of reach for us humans.