Koreamegops samsiki: New Fossil Spiders With 'Glowing' Eyes Found in South Korea

Friday, February 1, 2019

The defining specimen of Koreamegops samsiki, a newfound species of spider that lived in what is now South Korea between 106 and 112 million years ago. PHOTOGRAPH BY PAUL ANTONY SELDEN

The ancient arachnids had eyes that shone in the dark—a key adaptation for night vision.

IF YOU COULD time-travel to Korea 110 million years ago, you'd see an eerie spectacle if you walked out at night with a flashlight: Each sweep of your beam would make the landscape sparkle as innumerable spider eyes glinted in the dark.

In a new study in the Journal of Systematic Paleontology, a team led by Korea Polar Research Institute paleontologist Tae-Yoon Park unveils ten fossils of tiny spiders, each less than an inch wide. The remains contain two new species and a first for paleontology: a spider's version of night-vision goggles.

In some animals' eyeballs, a membrane called the tapetum (tuh-PEE-tuhm) sits behind the retina and reflects light back through it. If you've ever seen a cat's eyes seem to glow green at night, that's their tapeta at work. By giving the retinas a second chance to absorb light, tapeta boost the night vision of moths, cats, owls, and many other nocturnal animals. So, too, in these ancient spiders, whose silvery tapeta still shine in the fossils.

Two fossil specimens from the extinct spider family Lagonomegopidae had reflective eyes, a feature still apparent under light. Image credit: Paul Selden.

“They're so reflective—they clearly stick out at you,” says study coauthor Paul Selden, a paleontologist at the University of Kansas. “That was a sort of eureka moment.”

The find sheds further light on the ancient behavior of spiders, some of modern Earth's most important predators by mass.

“These fossils are extraordinary, and it’s always a thrill when something of the visual system is preserved,” Nathan Morehouse, a University of Cincinnati biologist who studies spider vision, writes in an email. “More exciting to me and other vision scientists is the glimpse that the tapetum offers into the lifestyle of these ancient animals. They were likely nocturnal hunters!”

The eyes have it

Some of the newfound spiders belong to an extinct group known as the lagonomegopids, some of which loosely resembled today's jumping spiders. The new fossils are the first lagonomegopids ever found in rock—all previous fossils of the group come from amber, or fossilized tree resin.

Source: www.nationalgeographic.com