If you stare into the eyes of a frog – maybe like Coyote does in this green tree frog video – you’ll notice the pupil staring back at you isn’t perfectly round.
Instead, green tree frogs have horizontal shaped pupils – just one of the eclectic mix of fans, diamonds and even hearts that help frogs see.
Why do frogs’ eyes have so many variations? Papers like this one by Dr Rayna Bell split the species into categories of pupil shapes, and then analysed how these weird and wacky variations evolved.
Spoiler – it’s incredibly difficult to work out, but they did discover some insights.
Human eyes have two important sections – the front and the back. The front has the cornea, pupil lens and iris. You might be interested to know that the iris is a type of sphincter, which is why it can dilate, and contract as required.
The back has the retina, fovea (depending on what type of animal you are) and the good old optic nerve to transport everything to the brain. The way this back section can process images is also quite astounding. The retina can pre-process images before it enters the brain, meaning that the retina – in some ways – is like a tiny brain.
Eyes – as Associate Professor Andrew Metha explains – also involve much more quantum mechanics than you might imagine.
But if you want to find out why, and how a species of algae and owls have the same shaped ‘eyes’ you’ll have to grab a copy of the magazine.
Cosmos Magazine #96 is available now at all good newsagents or subscribe at comosmagazine.com and save up to $35.
Jacinta Bowler is a science journalist at Cosmos. They have a undergraduate degree in genetics and journalism from the University of Queensland and have been published in the Best Australian Science Writing 2022.
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