One theory from that above White & Yamashita paper is that Boquila does this using plant ocelli—a very basic type of eye! If you’re interested in a brief infodump about ocelli: Many animals have ocelli, like jellyfish and insects. Here’s a picture of a wasp head—you can see its two main eyes to the side, and those three dots in the middle are ocelli.
(Photo cred: Assafn, Wikipedia)
These ocelli don’t form sharp images, but instead probably detect light and shadow for sleep patterns, directionality, flight stability, etc.
Some reptiles and amphibians also have a light-sensitive third eye called a parietal or pineal eye! It’s similarly right on top of their heads. Again, they’re not forming complex images, but instead use general light information to regulate other things. It’s also why even tame reptiles may bolt if you reach at them from directly overhead, out of range of their normal eyes—that third eye sees an incoming shadow and goes HAWK, RUN.
So with that in mind, plant ocelli…Basically they think the upper epidermal cells have evolved to have a particular convex dome shape that focuses light. I don’t know what proportion of cells are ocelli, if it’s just some or all, but basically the leaf itself IS the “eye”.
Plant ocelli were first proposed over a century ago but they haven’t been well studied since then. Cyanobacteria (a photosynthetic bacteria) focus light. Arabidopsis thaliana has been documented to recognize other Arabidopsis plants…basically when competing for resources, if the Arabidopsis recognizes it’s competing with other Arabidopsis plants, they’ll cooperate and move leaves so that they don’t shade each other, ensuring each plant has access to nutrients. But if the competing plant isn’t Arabidopsis, screw ‘em, they’ll shade it. Crepy & Casal narrowed this down to a light-based response, not just chemical identification, so it’s possible Arabidopsis is visually identifying friend from foe. At any rate, that’s about the extent of plant ocelli research that I was able to find. So this Boquila thing is cool and weird.
What we don’t yet know is how precisely Boquila is seeing the world. Boquila is clearly getting some level of resolution in order to be able to copy shape, size, AND color. Unlike an insect’s 2-3 ocelli, it has tons, so even crude data over a lot of inputs might lead to a pretty good picture. The paper also says the mimicry gets more accurate over time, so there appears to be some learning involved. I would also love to know if it has some equivalent of depth perception! If the target plant is near vs. far, does Boquila produce the same appropriately sized mimic leaf? Does it adjust? They’re going to keep studying it so hopefully we have some answers in a few years!
Anyway here’s a picture of the variation of Boquila mimic leaves.
(Photo cred: Gianoli figure)
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