Posted by admin | 12.05.2012 | Turtle Talk

There and Back Again: A Turtles Tale

You won’t normally find a sea turtle cozying up to you in coach and they rarely fit in those stubborn overhead bins, yet they are some of the world’s most extensive travelers. Sea turtles spend the majority of their lives roaming the world’s oceans; they are one of the ultimate maritime navigators.

Most species are constantly on the go, traveling thousands of miles to find nesting, foraging, and breeding grounds. The Australian flatback is the one big exception. This particular turtle tends to stay close to its native beaches. Its polar opposite is then, of course, the leatherback. Leatherbacks are migrating champions, known to journey over 12,000 miles in a single migration (too bad their not racking up frequent flier miles). This species often cross entire ocean basins in search of their favorite dinner – sea jellies.

Migratory patterns are species specific in the Cheloniodea superfamily. Green and hawksbill turtles are known to shuttle between specific nesting and foraging sites. Although some Japanese-born greens have been tracked making the 8,000 mile journey to the Baja Peninsula in Mexico before returning to the Asian continent as adults. Loggerhead and Kemp’s ridley migratory patterns usually incorporate a series of costal foraging sites that can stretch entire coastlines.

Patterns have yet to be established in leatherbacks and olive ridleys .These species tend to spend more time in open ocean following currents and food sources, they tend to travel passively versus the active patterns of their cousins. Research conducted using tracking devices shows that both species roam unpredictably mainly seeking food rich areas.

Though scientists disagree on exactly how sea turtles are able to navigate the world’s vast oceans so precisely most will agree they share one unifying characteristic, the ability to return to a specific nesting site year after year. A study conducted by researchers from Chapel Hill concluded that loggerheads do use the earth’s magnetic field to stay on coarse. It was discovered that loggerheads can do something truly amazing; they can determine both specific latitudinal and longitudinal locations (like an internal GPS). As of yet, we do not have sufficient evidence on other species to draw the same conclusion. Other navigational theories include utilizing light from the sun and stars, water temperatures fluctuations, and chemical olfactory signatures.

As the ocean is absent of road signs or highways, and I have yet to observe a sea turtle using Mapquest it is clear that turtle must have some sort of  very sophisticated internal compass. If not, then how can we explain their ability to repeatedly find a tiny patch of land in an otherwise vast and featureless ocean?