After tiny loggerhead turtles hatch from eggs buried on Florida beaches, they scramble frantically out to sea. Once in the open water, we see neither hide nor hair of these endangered turtles until they show up as teenagers on the other side of the Atlantic. But a new study, the first to track newborn turtles during these "lost years," has finally found out what happens. The mystery of sea turtles' "lost years" had long stumped marine biologists, including study author Jeanette Wyneken of Florida Atlantic University, who described the lack of existing data in a press release:
“From the time they leave our shores, we don’t hear anything about them until they are found near the Canary Islands. Those waters are a bit like nursery school for them, as they stay for about four to eight years. There’s a whole lot that happens crossing the Atlantic that we knew nothing about.”
So Wyneken and colleagues equipped newborn loggerhead turtles with tiny solar-powered transmitters, which allowed the researchers to follow their movements via satellite. Many of their findings confirmed previous theories, but this is the first real proof scientists have seen.
Black lines show the paths followed by individual turtle babies (109 to 281 days old). The colors represent water temperature. The inset shows the solar-powered transmitter on a test subject. Image credit: Wyneken, et al.
Unlike adult turtles, youngsters spent less than two percent of their time in Continental Shelf waters, where predators often lurk. Instead, the turtle tots often cruised on the Gulf Stream or on currents in another underwater superhighway, the North Atlantic Subtropical Gyre (like the one ridden by Crush and Squirt in Finding Nemo). The turtles seemed unconcerned about taking the most direct route across the Atlantic, though. They all traveled generally clockwise (probably using the Earth's magnetic field as a compass) but some individuals took shortcuts while others opted for scenic routes. The baby turtles often exited the superhighway to hang out in floating mats of seaweed called
at the ocean's surface. Researchers, already aware of these pit stops, had previously surmised that the greenery offered food and camouflage to protect the newborns from predators.
A Warm Blanket
What the researchers didn't realize was that in addition to these resources, the Sargasso Sea offers turtles much warmer waters. Tucked within the strands of seaweed, the turtles enjoy temperatures 4 to 6 degrees Celsius higher than the open ocean surface, according to their paper
published in Proceedings of the Royal Society B. Researchers think
that the extended periods of time spent here boost turtles' metabolisms, increasing their growth rate up to 50 percent. Plus, being exposed to the sun's UV light also provides the vitamin D necessary for the young turtles' shell development. Combined, these forces could trigger a real turtle growth spurt.
Image by Benjamin Albiach Galan / Shutterstock