Eyes of Dead Spiders are Still Shining after 110 Million Years

Researchers found brand new fossils of spiders in the Jinju Formation whose eyes are still shining 110 million years after their death.

It is incredibly difficult to explore ancient spiders because they are soft and don’t fossilize as easily as exoskeletons. That’s the reason why the scientists involved in this research were extremely fascinated upon discovering 10 new spider fossils in the Jinju Formation, which is a relatively unexplored part of the world. This extraordinary research was published in the ‘Journal of Systematic Palaeontology’.

Discovery of Spiders in the Jinju Formation

The researchers from the University of Kansas joined forces with the experts of the Korea Polar Research Institute to discover these new batch of fossils in the Jinju Formation, an ancient part of South Korea from the Mesozoic era. The finding has raised the number of spiders in this region from 1 to 11, which has certainly ignited the excitement of geologists from all parts of the globe. What made things even more thrilling is that the eyes of two of these spiders still reflect light. Paul Selden, a Geologist at the University of Kansas, referred to that by saying,

“Because these spiders were preserved in strange slivery flecks on dark rock, what was immediately obvious was their rather large eyes brightly marked with crescentic features. I realized this must have been the tapetum – that’s a reflective structure in an inverted eye where light comes in and is reverted back into retina cells.”

Eye Tapetum of these Spiders

Tapetum exists in the eyes of a number of animals but is missing in humans. For instance, the eyes of cats become increasingly shiny in dark due to the presence of tapetum. It is quite helpful for night vision and scientists believe that this is the first occasion when the preservation of spider eye tapetum has been done in the entire fossil record of the world. Selden explained the importance of tapetum in night vision in the following words:

“In spiders, the ones you see with really big eyes are jumping spiders, but their eyes are regular eyes – whereas wolf spiders at nighttime, you see their eyes reflected in light like cats. So, night-hunting predators tend to use this different kind of eye. This was the first time a tapetum had been in found in fossil. It’s nice to have exceptionally well-preserved features of internal anatomy like eye structure. It’s really not often you get something like that preserved in a fossil.”

Spiders in Amber

Generally, the fossils of ancient spiders are found in amber because it assists the preservation of the soft bodies. Having said that, the spiders with shining eyes were not discovered in amber and researchers believe that the tapetum might have been missed if they were present in an amber. The names assigned to these spiders are ‘Jinjumegops dalingwateri’ and ‘Koreamegops samsiki’. Selden talked about the special case which helped their tapetum to survive for so long and said,

“They don’t have hard shells so they very easily decay. It has to be a very special situation where they were washed into a body of water. Normally, they’d float. But here, they sunk, and that kept them away from decaying bacteria. These rocks also are covered in little crustaceans and fish, so there maybe was some catastrophic event like an algal bloom that trapped them in a mucus mat and sunk them – but that’s conjecture.”

Jumping Spiders

The researching team proposed that these spiders may have belonged to the same niche as of jumping spider in today’s world. However, they observed certain changes in their eye structure, which would have distinguished them from the jumping ones. Selden acknowledged that they were doing things differently and there are some variations in the structure of their eyes.

This discovery holds key significance because scientists hardly know anything substantial about the ancient crawlies of the Cretaceous Period due to the lack of fossils. Finding 10 new fossils in one go is a massive achievement of the researching team because it has given the scientific community a great opportunity to enhance their understanding of the spiders of that era.