Turtles tested on a teeny treadmill
If all goes well for newly-hatched sea turtles, it takes them only a couple of minutes to get from their nest to the ocean. If they get disoriented, however, they can spend up to several hours crawling around the beach before reaching the water. Will they still have enough energy left to swim sufficiently by the time they do so? To find out, scientists from Florida Atlantic University (FAU) put some hatchlings on a treadmill.
It is believed that sea turtle hatchlings instinctively move toward a bright low horizon and away from tall dark silhouettes, which puts them on a heading for the sea. Complications occur when artificial lighting in urban settings catches their attention, drawing them in the wrong direction.
Of the disoriented turtles that eventually do reach the water, a question arises as to whether they'll still have the energy to make it through the surf and evade marine predators. In order to answer that question, an FAU team led by Dr. Sarah Milton and grad student Karen Pankaew started off by collecting 150 just-emerged hatchlings from 27 loggerhead turtle and 18 green turtle nests on beaches in Palm Beach County.
Each turtle was subsequently placed on a miniature enclosed treadmill, on which it crawled in place toward a light source for the equivalent of at least 500 meters (1,640 ft). Based on field observations, that's approximately the distance that disoriented hatchlings typically cover before reaching the water.
They were then placed in a special "swimsuit," which held them in place while they swam in a tank. As they swam, the scientists counted their flipper strokes, plus they measured their breathing rate, oxygen consumption and lactate accumulation – the latter two were also measured while they were on the treadmill.
All of the hatchlings were released into the ocean as soon as the testing was over.
"We were completely surprised by the results of this study," says Milton. "We were expecting that the hatchlings would be really tired from the extended crawling and that they would not be able to swim well. It turned out not to be the case and that they are in fact crawling machines. They crawl and rest, crawl and rest and that's why they weren't too tired to swim."
That said, it's still not a good thing when they get disoriented. In such situations, up to 50 percent of the hatchlings are eaten by predators, run over by cars, or otherwise don't make it to the ocean.
A paper on the research was recently published in the Journal of Experimental Biology. The li'l treadmill-using turtles can be seen in action, in the following video.
Source: Florida Atlantic University