How sea animals navigate through the wide expanse of the ocean is an awesome mystery. In the blue vastness of the deep, they find invisible pathways to food and safe habitats.

One of the fascinating stories from the Blue Planet BBC documentary series
is one on Ridley sea turtles. The segment starts with a scene of the changing phases of the moon, whose both daily and monthly cycles influence the dynamics of the sea. For Ridley sea turtles, the moon serves as some kind of natural clock that is synchronized with their biological cycles.

Ridley sea turtles, now included in the International Union for Conservation of Nature (IUCN) endangered species list, practice a mass nesting method, also called an arribada. On a few nights each year, about a quarter of the world’s population of Ridley sea turtles come to a specific beach in the pacific coast of Costa Rica to lay their eggs. Brought in by the high tides, up to 400,000 female sea turtles would come within a few nights, laying 40 million eggs.

These are not random nights. They would come when the moon is either in its first or last quarter, between the new and full moon (or between full and new moon), and there’s a very good reason why. When the moon is neither full nor new, the tides are the weakest, and thus the water will not wash away the sand that covers the freshly laid eggs, subjecting them to vultures that come at dawn, trying to feed on washed off eggs. It’s a risk mitigation plan.

These sea turtles, while they’re not laying eggs, travel through the ocean during the year to search for food hundreds of miles away from this beach. But each year, in accordance with sea turtles’ tradition, they come back in packs and lay their eggs again, starting a new generation of sea turtles.

Watching them, my mind just kept asking the questions, Who tells them to go to Costa Rica? Who teaches them to go when the moon is not the strongest? As a believer, there is only One Master who can get the credit of coordinating this life system. But even knowing that answer doesn’t make this story any less baffling.

Knowest thou the time when the wild goats of the rock bring forth? or canst thou mark when the hinds do calve? Canst thou number the months that they fulfil? or knowest thou the time when they bring forth? Job 39:1-2

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