Umwelt

A tick crawling along the ground. Image taken at Ano Nuevo nature reserve.

Imagine for a moment that you were a tick. What would your world be like? A tick’s world consists of only 3 sensory cues. Three. First, they can detect light. This helps them to climb up tall grass to get higher off the ground and in a spot they are more likely to find a passing meal.

A tick now climbing up some blades of grass. Image taken at Ano Nuevo in California.

Once high up on a blade of grass, she waits for her second cue, the smell of butyric acid-a mammalian chemical by-product. When this smell comes by, she knows food is near and will drop off of her plant. An individual tick has been known to wait as long as 18 years for this precious cue.

Her last cue is warmth. Warmth indicates where blood is running close under the skin. Finding a warm spot, she burrows in, drinks the blood, drops off her host, lays her eggs and dies. She can’t taste the blood she’s been waiting so long for. In fact, she will drink any fluid that is the right temperature.

That’s it. Three things a tick can sense throughout its entire life. That’s its Umwelt, which is a term that means “the surrounding world” and is used to describe the unique and  limiting sensory world of every single animal species. Even within a species, individual animals can perceive the world differently.

A ticks Umwelt is incredibly simple. However because of this simplicity, her actions are unfailingly certain, with no distractions.

It’s wonderful to imagine what the world must be like to other animals. What do they experience that we don’t? What can we sense that they cannot? I plan to go into this in more detail in future posts. For the moment, consider our Umwelt and how very limiting it is. Even within our species, each of our brains is interpreting the world around us in a slightly different way. Sometimes before a stimulus even gets to our brains the hardware that captures it can be different between individuals. Take for instance our eyeballs. If we remove technology like glasses and lenses, think of how differently human beings would see the world. Even with those glasses and lenses there are differences.

We rely so much on our senses, it’s easy to imagine that the world holds only what we can experience. A great example of this is the discovery of color blindness. Although almost 10% of humans are color blind, color blindness wasn’t discovered until 1793, when a chemist named John Dalton, who had been working for years on colors of chemical compounds, realized that he himself was color blind. Imagine! It’s so easy to assume that everyone else senses what you do!

So next time you say the sky is blue and your friend says its purple, maybe they’re not being argumentative, maybe they’re telling the truth!