GLOBETROTTERS’ MAGNETIC MYSTERY

What molecule in a brain no larger than a pea helps birds navigate?

- DEEPIKA KOLLURU @Hyderabad

N moonless nights between February and April along Odisha’s coast, the sand begins to stir. Olive ridley hatchlings, no larger than a child’s palm, tear free from their shells and push through the sand to brave the foamy surf seaward. They have never tested these waters. No parent waits to lead them.

Yet, in minutes in shallow water, their bodies orient with startling precision, maintaining a steady offshore course into the Bay of Bengal, as if responding to a signal beyond sight.

This instinctive alignment to an unseen force recurs across the animal kingdom. Shorebirds descend from the steppes of Central Asia onto India’s wetlands. Warblers arrive from Siberia, navigating continents. Butterflies ride monsoon winds across peninsular distances. Each migration is steered by brains no larger than a pea.

Scientists call the phenomenon magnetoreception: the ability to sense Earth’s magnetic field. It is often described as biology’s most elusive sense. And the implications of its research are believed to reach far beyond animals.