and colleagues developed acoustic transmitters that are just 12 millimeters long, five millimeters wide, and weigh just half a gram. They glued these streamlined nano-tags (pictured above) onto 11 newborn loggerheads (Caretta caretta) from the island of Boa Vista in Cape Verde off the west African coast.
In just their first eight hours at sea, some hatchlings traveled distances of up to 15 kilometers. Their average travel speeds more than doubled from the initial 19 to 28 meters a minute up to 40 to 60 meters per minute when they joined the surface current flows passing near their natal areas.
As hypothesized, by the third night, the Cape Verdean hatchlings were essentially inactive at night. Previous work have shown that after the first day or so of the frenzy period, hatchlings become increasingly diurnal. Swimming during the day probably helps minimize predation risks, since many oceanic predators are the most active during twilight and nocturnal periods. Since the glue naturally breaks down, the tags detach from the babies' bellies after a few days.