This is Earth and Sky. Jeffery Polovina is a marine ecologist at the Pacific Islands Fisheries Science Center in Hawaii.

He tags sea animals to learn where they go, where they feed, and where they mate. The tags relay the data to scientists via a system of satellites.

Tags have revealed that loggerhead turtles travel back and forth across the Pacific Ocean along a transpacific "turtle highway." Polovina told us that turtles seem to congregate midway through their migration at a mid-ocean hotspot, just west of the international dateline.

It is just amazing that these loggerhead turtles, I think many of the other turtles as well, that we track, really seem to have a map of the ocean. We'll see them go into eddies, which are underwater cyclones and they'll ride around the edges of these eddies for a month at a time. These are big features. They will get off exactly where they got on. They will go through currents that move them north or south or east or west, but then they'll readjust their position.

Since the animals obviously know where important feeding and breeding places are, Polovina says scientists are thinking about using the animals to gather data that's typically collected by floating research instruments. He calls it "bio-logging" -- relying on fleets of animals instead of oceangoing research vessels.

That's our show. Join us in celebrating Earth and Sky's 15th anniversary and 5,000th radio show at . We are Block and Byrd for Earth and Sky.