Big Pacific – Mysterious Pacific

Watch the first episode of Big Pacific, “Mysterious Pacific,” tonight on PBS at 8pm Eastern. The companion book is now available from Princeton University Press.

The scale of the Pacific Ocean is almost incomprehensible. This single body of water covers a greater area than all six continents combined; its deepest point, the Marianas Trench, lies far further below the surface than the summit of Everest stands above it. Much of this vast realm is unexplored, inaccessible to the human eye, and even the shallow waters with which we are familiar are home to many strange and mysterious things.

Horseshoe Crab

The horseshoe crab – one of the planet’s “living fossils”

Among them are species that predate humankind, and indeed all mammals, by hundreds of millions of years. The four species of horseshoe crabs are the last remaining members of a family that first appears in the fossil record some 450 million years ago. Horseshoe crabs are not true crabs, being more closely related to arachnids such as spiders and scorpions. Despite their long tenure on this planet, horseshoe crab populations are in decline. Pollution, overfishing, and development along the Pacific shorelines where they mate are all taking a toll on these living fossils, and efforts are underway to protect them and improve their survival rate.

Nan Madol

The abandoned city of Nan Madol

Even the short span of human history presents enigmas. Off the eastern shore of the Micronesian island of Pohnpei lies the magnificent complex of Nan Madol. Comprised of over ninety artificial islets linked by a network of canals, Nan Madol is thought to have been home to the political and religious elite of Pohnpei. Construction of the complex was a monumental task: some 750,000 tonnes of black basalt were transported from the far side of Pohnpei to build monumental structures with walls up to 49 feet in height and 16 feet in thickness. More remarkable still, it seems to have been achieved without even the benefit of simple machines such as pulleys or levers—the building methods used remain unknown. Despite the enormous efforts that went into the building of Nan Madol in the twelfth and thirteenth centuries, the site was abandoned in the sixteenth century after the Saudeleur dynasty was toppled by invasion from without. Today it is a UNESCO heritage site.

Pufferfish circle

The tiny white spotted pufferfish at the center of his circle

Recent years have brought to light a smaller but no less fascinating construction project. In 1995 divers off the coast of Japan noticed unusual circular patterns in the seabed. Formed too perfectly to be the work of chance, these circles featured concentric rings of sand with furrows radiating from the central point like the spokes of a bicycle wheel. It was not until nearly twenty years later, in 2013, that the mysterious architect of these circles was identified. Despite the scale of the circles, up to six feet in diameter, they are the work of a species of small pufferfish, only a few inches in length. The male pufferfish works diligently, fanning the sand with his fins or using his body to shovel it aside, in order to construct his circle, which he then maintains carefully in the hope of attracting a mate. Even if he is successful in doing so, the female pufferfish does not stick around to admire his homemaking skills—having laid her eggs, she quickly departs leaving the male to care for and defend them.

With the vast depths of the Pacific largely unexplored, we can be sure that it has many more mysteries to offer us.

Watch the trailer to learn more.

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