Big Pacific – Passionate Pacific

Watch the fourth episode of Big Pacific, “Passionate Pacific,” on your local PBS station at 8pm Eastern, Wednesday, July 12th. The companion book is available now from Princeton University Press.

The largest ocean on planet Earth, the vast and unfathomable Pacific is inhabited by an extraordinary wealth and diversity of animal life. This multitude of species is united by a common drive—the need to reproduce—but that drive is expressed in ways as different as the creatures themselves.

Clownfish and Anemone

A clownfish lurks amid the fronds of a poisonous Anemone.

The home life of the clownfish is unusual—these small, brightly colored fish live out their lives amid the fronds of sea anemones, exuding a mucus-like covering that protects them from the anemone’s poisonous sting. Up to a dozen clownfish may live in the embrace of a single anemone, protected from predators by their host’s venom. In return, the clownfish consume parasites that could harm the anemone, and their movements as they swim help waft food towards the stationary anemone. All clownfish are born male, but within each of these miniature colonies, one of these males will become dominant and develop into a female. In turn, this female will select one and only one of the remaining males as a mate, leaving the rest to live out their lives in cloistered celibacy. The chosen male has the tasks of fertilizing the hundreds of eggs released by the female when she spawns and of guarding them without respite until they hatch ten days later.

Grunion run

Grunion carpet the shore during their mating run.

The reproductive life of the Gulf grunion is more hazardous and dramatic, played out in the liminal zone where the ocean meets the shore in the Gulf of California. Riding the high tide produced by the full moon, a wave of female grunion pitches onto the beach, digging into the sand to find a place to lay their eggs. That wave is followed in quick succession by the males, who wrap themselves around their half-buried mates to fertilize the eggs. Though the process takes only minutes, the fish quickly returning to the water to avoid suffocation, it leaves the grunion vulnerable. The beach, densely carpeted with silvery bodies, is an open buffet for predatory birds such as gulls, but the sheer mass of grunion ensures that plenty survive. The grunion hatchlings remain buried in the sand until the next full moon tide allows them to make their way back into the ocean.

Seahorses with tails entwined

Pot-bellied seahorses entwine their tails for a mating dance.

The Pot-bellied seahorse prefers a more relaxed courtship. Having identified a potential mate, the male seahorse brightens his stomach pouch to a vivid yellow. The female responds with her own display of color, and the two entwine their tails for an underwater dance that can last for up to twenty minutes as the seahorses pirouette and twirl around the warm, shallow waters in which they live. At the consummation of the dance, the two belly-to-belly, the female squirts her eggs into an opening in the male’s pouch and the two separate. Once the eggs hatch, the male carries his hundreds of offspring in his pouch for up to a month, before releasing them to float away.

This post is part of a series, explore additional posts here<< Big Pacific – Voracious Pacific