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I write about a lot of different topics, but often as not, I find myself devoting a few pages to writing about seeing. Maybe that’s not surprising given that most folks read comics by looking at them, but nevertheless. I’ve covered how dogs see, how cats see, how trees see, and while working on my latest, I’ve gotten to go more in depth than ever before. Yet there’s always that pesky page count to look out for. There plain isn’t room to include every interesting facet of a topic! So today I’d like to share something weird and cool that, small as it is, just didn’t fit. Call it Appendix A.

We can all agree that eyes are complicated, right? They are, after all, goo balls capable of registering minute variations in the properties of electromagnetic waves. Complicated is appropriate. Humans as a species, though, are more visually adept than most other Earthlings. Our eyes shouldn’t be the standard by which all others are judged. Many species achieve all they need to with less compex eyes.

Think of dogs! They have just two cone types — color sensitive light receptors — compared to humans’ three. Whales get by with just one (it’s all blue down there). Forget color, even. The ability to tell light from dark is a huge advantage by itself. Sea urchins have simple light receptors at the tip of each spine. Knowing the difference between bright, open water and a safe, dark crevice is enough to give them a leg up (spine up?) on their predators.

So how simple can a useful “eye” be? What’s the lower limit on vision? As it turns out, you don’t even need to be multicellular to see.

Biologist Nils Schuergers and co. describe microbes of the genus Synechocystis, phototrophic cyanobacteria (ones that live on sunlight) found in freshwater lakes. The body of a Synechocystis is a single spherical, transparent cell about three microns across. Although aquatic, they can’t swim, instead extending tentacle-like flagella to drag their way through the world, ideally toward somewhere getting just the right amount of sunlight to live on.

This is where you might wonder how a microbe can tell where that just-right light is. For Synechocystis, the answer is simple: they look for it.

These microbes are essentially all eye, their outer membrane acting as both lens and cornea. They can get away with that, being curved, clear, and dotted with light-detecting sites. As far as humans go, light can only enter the eye through the pupil. We have to face something to see it. That light passes through a curved lens that focuses it at the back of the organ.

Synechocystis looks everywhere at once. Any side of their body will focus light on its opposite side, and there’s always a photoreceptor ready to receive it. All this even though they barely outsize the wavelength of visible light itself!

Synechocystis doesn’t see the world in any real detail, mind you, and they certainly don’t have the tools to perceive images like we do. However, their only concern is finding the sun. Being 100,000 times brighter than anything else in nature, it’s hard to miss.

One complicating factor is that a being this size doesn’t have room for very many photoreceptors. A human photoreceptor is about as big around as one these little fella’s whole body. With relatively small numbers of relatively small receptors, it takes Synechocystis ten to twenty seconds to catch enough photons to act on. At that rate, Titanic is over a month long. Who has the time?

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What’s this? A puzzle section? Call it a peek at something very, very exciting I have in the works. Solve this Strands-type wordfind by linking adjacent letters (diagonal is okay) to find five separate words. Put them in the right order to get the title of my upcoming brand new series! You could also check Publishers Weekly, but that isn’t really in the spirit of things. Good luck!