Naturally Kiawah Magazine Volume 36 | Page 28

roots to the seabed, planktonic creatures mostly drift, though as those World War II pings revealed, some are masters at swimming up and down. Many forms of plankton are so tiny you need a microscope to see them, but they are the unsung heroes of the planet’s air. You can thank species of sun-loving plankton for the breath you just took. Until about two billion years ago, the planet’s atmosphere was breathlessly devoid of oxygen. But then a distant cousin of today’s blue-green algae began using the sun’s rays to split water into hydrogen and oxygen. Earth hasn’t been the same since. Today, half of the atmosphere’s oxygen comes from ocean plankton—every other breath. Plankton comes in all shapes and sizes, but scientists divide them into two categories. Phytoplankton are the microscopic algae and other cells that drift in the sun-infused upper layer of the ocean. Think of them as the plants of the sea, the oxygen producers. Zooplankton are the larger animals that typically feed on the phytoplankton. Think of them of the sea’s insects, snails, and worms. Small and large, plant and animal, they do amazing things. One zooplankton called phronima chomps on smaller plankton and uses their body parts to make protective cellulose barrels. The mother lives in the barrel, zealously guarding her young, while males bolt at the slightest danger. zooplankton species has little blue sails; washing up on the beach, their colonies look like a regatta of tiny blue boats. Another jellyfish can literally reverse its aging process; its nickname is “the immortal jellyfish.” When phytoplankton die, they emit cloud-forming chemicals that give beaches their intoxicating and briny smell. Some phytoplankton also are killers: Shaped like glistening needles, they secrete neurotoxins that find their way into shellfish and animals that feed on them. After one toxic algal bloom in 1961 in Monterey Bay, Calif., thousands of poisoned seabirds dive-bombed houses and cars and piled up dead on streets. The phenomenon inspired Alfred Hitchcock’s movie, “The Birds.” Counting plankton is like counting stars, though instead of stars, some species look like Christmas ornaments and the Leaning Tower of Pisa. A single teaspoon of seawater might contain a million phytoplankton bacteria and 100 million planktonic viruses that feed on them. Viruses alone have an overall biomass in the oceans of 75 million blue whales. Mostly unseen, these hordes of planktonic algae and viruses are in a constant state of biochemical warfare: The viruses attack the algae while the algae develop special plates of armor. Much of what we know about plankton has been discovered since World War II, thanks in part to those curious Division 6 scientists, but also because of people like Dennis Allen, who one morning in January, stands in a johnboat in a South Carolina marsh, wondering: Why does the water look so weird? Curiosity and the Long View Phronima’s fierce appearance is the inspiration for the creature in the movie “Alien.” Some algae and bacteria have red pigments and grow so dense they color vast areas of the ocean; floating pink blankets of bacteria gave the Red Sea its name. One 26 Dennis Allen is resident director of the University of South Carolina’s Belle W. Baruch Marine Field Laboratory, a scie