Category Archives: Animal World

Nature’s Most Amazing Eyes Just Got A Bit Weirder

Eyes are testaments to evolution’s creativity. They all do the same basic things—detect light, and convert it into electrical signals—but in such a wondrous variety of ways. There are single and compound eyes, bifocal lensesand rocky ones, mirrors and optic fibres. And there are eyes that are so alien, so constantly surprising, that after decades of research, scientists have only just about figured out how they work, let alone why they evolved that way. To find them, you need to go for a swim.

Eyes of the peacock mantis shrimp. The black bands show where it's looking. Credit: Mike Bok

This is the eye of a mantis shrimp—an marine animal that’s neither a mantis nor a shrimp, but a close relative of crabs and lobsters. It’s a compound eye, made of thousands of small units that each detects light independently. Those in the midband—the central stripe you can see in the photo—are special. They’re the ones that let the animal see colour.

Most people have three types of light-detecting cells, or photoreceptors, which are sensitive to red, green and blue light. But the mantis shrimp has anywhere from 12 to 16 different photoreceptors in its midband. Most people assume that they must therefore be really good at seeing a wide range of colours—a “thermonuclear bomb of light and beauty”, as the Oatmeal put it. But last year, Hanna Thoen from the University of Queensland found thatthey’re much worse at discriminating between colours than most other animals! They seem to use their dozen-plus receptors to recognise colours in a unique way that’s very different to other animals but oddly similar to some satellites.

Thoen focused on the receptors that detect colours from red to violet—the same rainbow we can see. But these ultra-violent animals can also see ultraviolet (UV). The rock mantis shrimp, for example, has six photoreceptors dedicated to this part of the spectrum, each one tuned to a different wavelength. That’s the most complex UV-detecting system found in nature. Michael Bok from the University of Maryland wanted to know how it works.

On Earth, Total Weight of Ants = Total Weight of Humans

ants High Hopes

 

Unless you leave food out and attract them, humans rarely have a need to think about ants. They’re tiny, not poisonous and not particularly terrifying, like say, spiders. However, they far outnumber humans on earth–by one million to one!

Funnily enough, they are also roughly a millionth of a human in size too. Do the math–the total weight of all the ants on earth matches the total weight of the entire human population.

There are 10,000 different types of ants and they’ve been around for a long time. Ancients ants have been discovered in fossilized sap from 100 million years ago!

Over time, ants have changed very little. Their way of life and survival is successful. Some scientists attribute this to their unselfish ways. Ants live in colonies and bring their prey back to their many relatives to share.