Retell Lecture

It is time for this young loggerhead Turtle to go to work. We can tether turtles in these little cloth harnesses. put them in this tank and they’ll swim in place. University of North Carolina Biologist Ken Lohmann studies sea turtles that are programmed from birth for an extraordinary journey. The mother turtles bury the eggs on the beach and then return to the sea and the eggs hatch about 50-60 days later. With support from the National Science Foundation, Lohmann is learning how these reptiles use the Earth magnetic field to navigate a 5-10-year journey around the Atlantic Ocean. The turtle seems to inherit a set of responses that tell them what to do when they encounter specific magnetic fields at particular locations. This animal magnetism can be a life saver, one filed off Portugal triggers the turtles to turn south, if they don’t, they will likely die, swept into frigid North Atlantic waters. In one lab test, turtles responded to magnetic fields similar to what they would encounter off the coast of Florida. The great majority of them turned southeast. Now, this is an exciting finding because south easterly orientation in this part of the world, would presumably take turtles further into the Gulf Stream. So the turtles actually have, what might be considered, a crude global positioning system that is based on the Earth's magnetic field. And check out this experiment, these turtle moves may look odd. The turtles will actually act out their swimming behaviour in air. But this wave simulator recreates the first environmental cue hatchling turtles respond to, and so swimming into waves is a highly reliable trick that turtles use to guide themselves offshore.