The mantis
and the bird
So how does it miss the bird behind it?
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The full narration of the video.
The mantis has such big eyes. So how did it miss the bird behind it? This story first appears in the Zhuangzi, an ancient Chinese classic. One summer, a cicada sits in the shade, singing its heart out.
A mantis creeps up behind it and raises its two blades. And behind the mantis, a bird is watching. Later tellings called it a yellow sparrow. Mantises really do eat cicadas, and birds really do eat mantises.
So why didn't the mantis notice? Let's replay the hunt through its eyes. Each of those big eyes is built from a mosaic of tiny eyes. The ones around the edge see blurry, but they're very good at spotting movement.
The cicada's wing twitches, and the edge of the eye catches it first. The mantis snaps its head around and puts the cicada straight ahead. That small patch in front has the most tightly packed eyes. It sees about four times sharper than the edge.
It's like tapping your phone screen to focus. That one spot snaps sharp. Before striking, it uses both eyes together to judge how far away the cicada is. A little off, and the blades close on air. So its head and eyes are locked on the cicada.
And it has to stay perfectly still. One wrong move, and the cicada is gone. Right then, the bird edges in from behind. The eyes facing back see the blurriest. And the bird moves slowly, barely a flicker.
More importantly, its whole mind is on the cicada. Scientists fitted mantises with tiny 3D glasses and showed them little dots on a screen. Flash something on one side first, and a dot on the other side gets far less reaction.
Pull its attention one way, and the other side gets ignored. This is called selective attention. People do it too. In a famous test, viewers counted basketball passes. Someone in a gorilla suit walked through, and about half of them never saw it. The focus box is your attention. Everything blurred outside it is what you didn't get to.
Many animals face this trade-off: more time eating, less time looking up. So the mantis isn't blind. It's busy. With its eyes and mind on the cicada, its back is left to luck. But the story isn't over. In the Zhuangzi, the one aiming a slingshot at that bird was Zhuangzi himself.
While he was lost in the moment, the orchard keeper ran up behind him and gave him an earful. When you lock onto one thing, anyone can be the mantis. If you were the mantis, would you glance back before striking, or grab the cicada first?
Not blind,
just busy
On a summer tree, a cicada sings away. A mantis creeps up behind it and raises its two blades. Behind the mantis, a bird is watching too.
The mantis gives its eyes and its mind to the cicada. What is behind it is left to luck.
This Chinese saying, "the mantis stalks the cicada, unaware of the oriole behind," comes from the Zhuangzi, a book written over 2,000 years ago. The original just says "a strange magpie"; later tellers made it an oriole. Mantises really do eat cicadas, and birds really do eat mantises.
Big eyes,
one sharp spot
Each big mantis eye is made of thousands of tiny eyes. They are not packed the same way all over.
to catch movement
about four times sharper
Put simply: the edges catch motion, the front sees detail.
Like tap-to-focus
on a phone
When you take a photo, you tap one spot. That spot snaps sharp, and the rest goes soft.
A mantis does the same before it strikes. Its head and eyes all point at the cicada. It also uses both eyes together to judge how far away the cicada is. A little off, and the blades grab air.
Why the bird
slips past
Scientists fitted mantises with tiny 3D glasses and showed them small dark dots on a screen. A flash on one side pulled the mantis's attention there. Then a dot on the other side got mostly ignored.
People too:
the focus box is attention
What sits in the focus box is what you pay attention to. What blurs outside it is what you miss.
Quick check
Why does the striking mantis miss the bird behind it?
Like tap-to-focus: the cicada in the box is sharp, the bird outside it blurs. The mantis isn't blind, just busy.
