How Does a Snake “See” in the Dark?

viaadmin Volume 43

We can’t usually see in the dark. Why not?

You’re probably thinking, “Because there’s no light!”

Well, actually, you’re wrong…there’s lots of light, it’s just not the type that we normally use to see with! Let’s talk a bit about light and start with the sun.

Our sun is a ball of mainly hydrogen gas. Inside the sun, burning hydrogen releases electromagnetic radiation. Visible light, the red-to-violet colours of the rainbow, is one type of electromagnetic radiation. We use it to see. Another type of electromagnetic radiation is infrared light. We can’t use infrared light to see, but when it is absorbed by our skin, we sense it as heat. Any warm object (like a pot of tea or a person) will release infrared light, but only hot objects (like the sun, a light bulb filament, or a wood fire) release visible light.

A snake’s eyes also use visible light to see. But some, such as rattlesnakes, have something extra – pit organs. These are little pits near the nostrils. Infrared light from the snake’s surroundings enter the pits and are converted into electrical signals. These signals then go through other nerves to the same part of the brain where signals from its eyes are sent.

Because a mouse is warmer than the background around it, the infrared light it releases is different than that released by the background. You can think of it as the mouse having different infrared colours than the background. So, if there was a mouse in the dark, even though we can’t see it, the snake, using its pit organs, can “see” the mouse…and then have a tasty snack!

The ability of some snakes to see in the dark by making use of a type of light that is in the dark reminds me of another light that we read of in the Bible.

Jesus said, “I am the light of the world. He who follows Me shall not walk in darkness, but have the light of life” (John 8:12). If we don’t know the Lord Jesus as our Saviour, it’s as if we are walking in darkness. To walk in darkness is to live a life that is apart from God, condemned by God for our sin (John 3:18).

John 1:9 tells us that the true Light, the Lord Jesus, is come into the world. Like the infrared light, this Light is constantly shining in the darkness (John 1:5) and will make what is in the dark, our sins, visible to us (John 3:20). When we learn about the Lord Jesus in the Bible, we begin to understand how sinful we are, just as when a light shines and shows us something we couldn’t see before. When we trust Christ as our Saviour, the problem of our sin is taken care of and we no longer walk in darkness.

May you discover that the Lord Jesus, this Light, is available for you today!

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