Armor is nothing new in the animal kingdom but a group of sea creatures called chitons have evolved armor that is made up hundreds of eyes with lenses made of rock that require replacement do to erosion.
Chitons are just strange
This “all seeing” chiton is a mollusk making it a relative of octopi, clams, and snails. The oval bodies of the chiton are protected by a series of overlapping plates design to protect the creature. However, what makes these plates special is that these plates or dotted with tiny eyes that resemble beads, these beads while visible to the naked eye measure less than .10 millimeters in diameter. Somewhat surprisingly, scientists have been aware of these eyes with lenses, retinas and a layer of dark pigment. However, they had no idea whether or not these eyes were capable of “sight.”
That changed when a graduate student at the University of California, Santa Barbara named Daniel Speiser dissected the eyes of a chiton and then tried to clean them with acid. Rather than finding them cleaner, Mr. Speiser realized that they were no longer there, poof….disappeared into thin acid bath. The “rocky” lenses are actually made from aragonite, a mineral that is related to limestone.
Speiser learned that these eyes can certainly detect light and believes them also capable of seeing the rough form of objects. Imagine them as really poor resolution eyes with hundreds of them for backup, unless, of course, the mollusk can put together an image from all of them in a sort of collaboration.
Speiser finds partners to look at the chiton
Speiser found to MIT grad students in Ling Li and Matthew Connors to take a futher look into the capabilities of the chiton eyes using an x-ray scanner that MIT presumably has lying around the campus. What they discovered with tech I don’t understand is that “They’re forming decent images in an animal that, to be really blunt, is not that smart.”
Through further study, the team learned that the chiton can indeed form heavily-pixellated images that by definition are quite blurry. But where the chiton lives it doesn’t need to be watching “Frozen” in HD with the kids. Li and Connors believe that the eyes could produce better resolution but that would come with the caveat of weaker armor. So the chiton is walking the line of vision and defense that has evolved over time.
“A chiton doesn’t have many … behavioral outputs,” says Speiser’s graduate advisor, Sonke Johnsen of Duke University. “It can wander around, graze, and glue down onto a rock. That’s about it. Why something that only really needs to tell if a predator is round is building all these really beautiful crystal lenses, and paying the price of making their armor not as strong, is a really good question.
It goes against the general paradigm that the world is divided into dumb animals without heads and not a lot of sensory capabilities, and smart animals with heads that move around and have sharp sense,” he adds. “There are all these animals that don’t fit these categories. They open our eyes up to new ways of solving the same problems.”