Baby Turtles Have Been Wearing the Same Color for 50 Million Years
December 7, 2017
Preserved tissue found in a turtle fossil shows that sea turtle hatchlings have been relying on a dark color to help them survive for millions of years.
Some things are destined to go out of style. Coats with shoulder pads, like bell-bottom jeans and bowler hats before them had their time. By the time my hair grows out, man-buns may no longer be in vogue.
It turns out, however, that fashion runs on a far slower clock if you’re a sea turtle; so slow in fact, that they’ve been wearing the same color for 54 million years.
Researchers from NC State University, as well as universities in Sweden and Japan, analyzed preserved tissue from a 54 million-year old sea turtle hatchling, and found that both ancient sea turtles and modern sea turtles share a dark pigment in their shells. A paper describing the research was published in the journal, Scientific Reports.
This is the point where you’re most likely asking yourself why a team of scientists would spend their time subjecting a turtle fossil to more than half a dozen chemical and imaging analyses (which they did, by the way) to figure out what color it was. And why anyone should care? As it turns out there are plenty of reasons, starting with the one that made this study possible.
Fossils, by definition are either imprints left in rock or mineralized — that is, completely turned into rock — remains of living organisms. This particular sea turtle fossil was so well preserved that it actually contained a very thin film of 50-million-year-old soft tissue: actual cells from an ancient sea turtle. That fact in and of itself is revolutionary. It opens up new possibilities for what paleontologists can learn from fossilized remains if they can find even tiny amounts of tissue sandwiched in between the rock and bone of the fossil.
The second reason is because of how that dark pigment might have fit into the survival strategy of ancient sea turtle hatchlings. Modern sea turtles rely heavily on the dark color of their shells to survive. Dark shells help sea turtles blend in with the dark water of the ocean, camouflaging them from seagulls and other predators that would grab them from above. On a molecular level, the researchers found a molecule that both protects the turtle from ultraviolet light and absorb heat, allowing them to digest and grow more quickly. This color might be the comfortable flats or belt-that-goes-with-anything of the turtle world: a timeless classic that provides fashion and function.
Turtle pigments are also interesting because of the perspective they provide to the evolutionary timeline of turtle. While that may seem ultra-academic, the sheer ancientness of sea turtles is mind-blowing to think about. This research shows that shell pigment has been a survival trait in sea turtles for more than 50 million years. The first primates came into being around the same time as shell pigment. They began to walk on two legs only 5 million years ago, use tools 2.5 million years ago and talk 150,000 years ago. If turtles with their dark pigment are the evolutionary black dress, speech shows up somewhere in infinity scarf or thick-rimmed glasses territory. It is astounding to think how much more ancient and evolutionarily steady turtles, and other animals like crocodiles are than humans.
By comparison, we humans seem to move so quickly, and things we love will inevitably fall out of favor with the fashionable. Someday, skinny jeans and plaid flannel shirts will go the way of parachute pants and big hair. But if you ever get tired of trying to keep up fashion, just remember to dress dark, and be a turtle.
Daniel Lane covers science, medicine, engineering and the environment in North Carolina.