After swimming out to the open ocean, hatchlings get swept into convergence zones, areas where surface waters are driven into each other by currents or the wind. Convergence zones are also known as weedlines because they collect sargassum, a brown floating seaweed. Weedlines range from being relatively small and ephemeral narrow strips a few hundred feet long that last only while the wind blows to being vast and essentially permanent. Where the Gulf Stream swirls up to the central north Atlantic, weedlines can be a dozen miles long and several miles wide, and so persistent that the area is called the Sargasso Sea. For the few hatchlings that survive the gauntlet of the predator-filled beach and nearshore waters, weedlines are a haven.
Few predators lurk in weedlines while prey abounds.
Unlike adults, green turtle hatchlings are carnivorous and feed on all kinds of creatures from worms to crustaceans to insects. The baby turtles just float around and eat and grow until they reach eight to ten inches, which typically takes several years. Then they undergo a dramatic change, switching to a vegetarian diet of sea grass and algae and abandoning the weedlines for the adult grazing grounds. Carr didn t muse about a fifth sea turtle mystery, presumably because he knew the answer. But generations of children have wondered why the mock turtle in Alice in Wonderland is always crying.