Strange and wondrous creatures: plankton and the origins of life on Earth

Without plankton, the modern ocean ecosystem – the very idea of the ocean as we understand it – would collapse. Earth would have no complex life of any kind

When I arrived at Wickford Harbor in North Kingstown, Rhode Island, early one June morning, the sea was moderately calm, with a distinct metallic sheen, like a wrinkled sheet of foil someone had tried to rub smooth. Vitul Agarwal, a young oceanographer, waved to me from beside a research trawler with the name Cap’n Bert painted on its hull. Dressed in jeans and a diamond-patterned sweater, Agarwal welcomed me aboard and introduced me to the captain, Steve Barber, whose grey hair spilled from the back of a baseball cap.

A few minutes later, we motored slowly into Narragansett Bay. The sun was low. Directly behind the boat, the sea churned shades of grey and green. “I think we’re going to find a lot out here today,” Agarwal said, gesturing toward our frothing wake. “Because of the colour?” I asked. He nodded.

Every week since 1957, in one of the longest-running surveys of its kind anywhere in the world, scientists have come to this exact spot to study some of the most abundant and important life forms in the ocean: creatures so tiny that the vast majority are invisible to the naked eye, yet so essential to Earth’s ecosystems that our planet would be virtually barren without them – creatures we call plankton.

Plankton, from the Greek planktos for “wandering” or “drifting”, are a large and diverse collection of water-dwelling organisms that tend to flow with currents and tides. Nearly every liquid environment on the planet is home to plankton: the ocean, of course, but also rivers, lakes, wetlands, geysers, ponds, puddles and even raindrops. Although most plankton are microscopic, a few large animals also qualify as plankton because they are such listless swimmers. Bacteria and viruses populate the smallest end of the plankton spectrum. Certain jellyfish and their relatives, some of which are more than 40 metres long with their tentacles fully extended, inhabit the other. In between bobs a panoply of strange and wondrous creatures, many of which are little known and poorly studied – despite their power to change the planet.