The Drifters

Plankton planet: Meet the creatures who make up 98 percent of the oceans’ biomass. /

Even when God makes a little thing, it is great because of the wisdom displayed in making it. The microscope has taught us the greatness of God in creating tiny creatures of wondrous beauty, yet so small as not to be perceptible to the naked eye. “The works of the Lord are great.”
—Charles Spurgeon, Exposition of Psalm 111

Take two breaths. For one of them, you can thank the plankton, in particular the single-celled photosynthetic drifters that compose the phytoplankton of the world ocean. Remarkably, these elegant, microscopic cells perform nearly half of the photosynthesis and consequent oxygen production on Earth—equivalent to the total amount of photosynthetic activity of land plants combined. These tiny single cells have transformed the ocean, atmosphere, and terrestrial environment and helped make the planet habitable for a broad spectrum of other organisms, including ourselves. In many cases, blooms of phytoplankton reach such densities that they change the color of ocean surface waters and are even visible from satellites orbiting Earth.

Every schoolchild knows that baleen whales, the biggest animals in the sea, subsist on huge quantities of krill, which are small zooplankton. But ocean food webs (the linkages between predators and prey) are far more intricate than this familiar example. Many types of plankton eat other plankton. . . . Some plankton have the ability to function as plants (carrying out photosynthesis) and animals at the same time. Others secrete elaborate mineral skeletons of calcium carbonate or silica. Still others live in complex symbiotic relationships with partner organisms. One type of gelatinous zooplankton—the appendicularians—has remarkably fine mesh feeding filters that trap the smallest bacteria in the ocean, leading to a size difference between the consumer and prey comparable to the size difference between whales and krill. Most fishes also eat some types of planktonic prey, especially in the crucial larval stages when availability of just the right kind of zooplankton at the right time and place can determine their survival.

When Pyrocystis lunula is disturbed, it glows with a beautiful blue light.

When Pyrocystis lunula is disturbed, it glows with a beautiful blue light.

This collection of plankton not only includes both unicellular and multicellular organisms, but shows some of the variety even between the unicellular creatures: star-shaped radiolarians; cylindrical, spherical, and chain-like diatoms; and anchor-shaped dinoflagellates.

This collection of plankton not only includes both unicellular and multicellular organisms, but shows some of the variety even between the unicellular creatures: star-shaped radiolarians; cylindrical, spherical, and chain-like diatoms; and anchor-shaped dinoflagellates.

The shells of these tintinnids may call to mind champagne flutes, but they reminded earlier researchers of Roman soldiers’ clothing, from which they derive their name (loricae).
Image: John Dolan, CNRS , Observatoire Océanologique de Villefranche-sur-Mer

The shells of these tintinnids may call to mind champagne flutes, but they reminded earlier researchers of Roman soldiers’ clothing, from which they derive their name (loricae).

The large yellowish dome-like creatures are single-celled phytoplankton known as diatoms (specifically Coscinodiscus sp. and Hemidiscus sp.). Those long Tetris-like chains of Skeletonema sp. are diatoms as well. But the bright pink spiky creatures are Protoperidinium depressum— dinoflagellates that eat diatoms. At the center of this image, next to the yellow star-shaped radiolarian, is a barnacle larva.

The large yellowish dome-like creatures are single-celled phytoplankton known as diatoms (specifically Coscinodiscus sp. and Hemidiscus sp.). Those long Tetris-like chains of Skeletonema sp. are diatoms as well. But the bright pink spiky creatures are Protoperidinium depressum— dinoflagellates that eat diatoms. At the center of this image, next to the yellow star-shaped radiolarian, is a barnacle larva.

A polycystine radiolarian.

A polycystine radiolarian.

This ten-legged crustacean has survived several weeks to emerge from its larval stage as a megalopa. It’s not yet an adult. But throughout its life it has been and is still planktonic.

This ten-legged crustacean has survived several weeks to emerge from its larval stage as a megalopa. It’s not yet an adult. But throughout its life it has been and is still planktonic.

Light reflects and diffracts through tiny plates on the male Sapphirina copepod, letting it disappear or turn bright colors.
Image: Sharif Mirshak, Parafilms, Montreal

Light reflects and diffracts through tiny plates on the male Sapphirina copepod, letting it disappear or turn bright colors.

Star-shaped chromaophores turn the Phronima amphipode’s claw red.
Image: Christian Sardet and Sharif Mirshak

Star-shaped chromaophores turn the Phronima amphipode’s claw red.

Like a hermit crab, the female Phronima is a squatter. But instead of occupying a ready-made snail’s shell, Phronima builds a barrel using the envelope of its gelatinous host. The cartoonist Moebius was inspired by Phronima’s form, and his drawings were used to create the monster in Alien.

Like a hermit crab, the female Phronima is a squatter. But instead of occupying a ready-made snail’s shell, Phronima builds a barrel using the envelope of its gelatinous host. The cartoonist Moebius was inspired by Phronima’s form, and his drawings were used to create the monster in Alien.

Atlanta peronei, a mollusk species common near the French Riviera, has a flattened foot that serves as a swimming fin.

Atlanta peronei, a mollusk species common near the French Riviera, has a flattened foot that serves as a swimming fin.

Firola, the “sea elephant,” is one of the largest planktonic mollusks, and can grow to about a foot.

Firola, the “sea elephant,” is one of the largest planktonic mollusks, and can grow to about a foot.

Call it a young nudibranch or call it a young sea slug—both names are common. Specifically, it’s part of the genus called flabellina. And it too is part of the plankton world.

Call it a young nudibranch or call it a young sea slug—both names are common. Specifically, it’s part of the genus called flabellina. And it too is part of the plankton world.

This European squid (Loligo vulgaris), about 4 or 5 millimeters long, has just hatched but is already showing red and yellow pigment cells that will let it change its color at will.
Image: Sharif Mirshak, Parafilms, Montreal

This European squid (Loligo vulgaris), about 4 or 5 millimeters long, has just hatched but is already showing red and yellow pigment cells that will let it change its color at will.

A pyrosome is not one animal but a colony of hundreds of separate multicellular animals traveling together. They can move a bit through jet propulsion, but (as with all plankton) their movements are mostly determined by the movements of the sea.

A pyrosome is not one animal but a colony of hundreds of separate multicellular animals traveling together. They can move a bit through jet propulsion, but (as with all plankton) their movements are mostly determined by the movements of the sea.

Christian Sardet is cofounder and emeritus research director of the Laboratory of Cell Biology at the Marine Station of Villefranche-sur-mer and creator of the Plankton Chronicles project.

Mark Ohman is professor of biological oceanography at University of California, San Diego.

Excerpted from the prologue to Plankton by Christian Sardet (University of Chicago Press, 2015) with permission from the publisher. Spurgeon epigraph added by the editors.

Follow The Behemoth on Twitter and Facebook.

Also in this Issue

Issue 30 / September 3, 2015
  1. Editor's Note from September 01, 2015

    Issue 30: Picturing plankton, the rarely told story of the first missionary to the Muslims, and the arresting burning bush. /

  2. Before We Conquer, Have We Tried Love and Prayers?

    Remembering the first missionary to Muslims, 700 years after his death. /

  3. Stay By the Fire

    The God who makes himself known as flame wants to hold our gaze. /

  4. The New Creation

    ‘A choir of a thousand tongues / singing we’ll no longer toil.’ /

  5. Wonder on the Web

    Wonder on the Web Issue 30: Links to amazing stuff /

Issue Archives