There’s many a way to navigate the open sea, even sans GPS or a compass. On a clear night, the prow can be steered according to the North Star. During the day, a keen ornithologist can figure out the directions by looking at the right migratory bird. Even the humble and delicious salmon, as they swim back to where they were born, to reproduce, can theoretically provide both sustenance and guidance to a weary traveller. Thankfully, not all the pilgrims of the natural world are such efficient overachievers. Hawksbill turtles know instinctively what annoying Instagram posts about wanderlust have just discovered recently: It’s the journey that matters.
How animals like sea turtles know where to go has occupied the attention of naturalists and researchers for centuries. Broadly speaking, there is no definitive answer. Birds likely have something like an internal GPS that guides them, salmon probably imprint on the magnetic coordinates of their home river. The hawksbill turtle, earlier research had suggested, had a cartographic mechanism similar to the latter. But according to researchers who have tracked them on the open ocean, they “almost certainly are using a geomagnetic map, but it’s a fairly coarse resolution”. To get to a destination that is just 176 km away, they swam for about 1,300 km.
This editorial first appeared in the print edition on May 13, 2022 under the title ‘The turtle’s way’.
