If you’ve never seen luminous squid or spiny lobsters swimming in anything other than melted butter, if you’ve never met a giant grouper face-to-face, it might not occur to you why some of us feel a profound loss that many coral reef dwellers—and the reefs themselves—are fast becoming history.

Like a jeweled belt, reef-forming corals and their plant partners thrive around the planet’s warm midsection—usually in clear water less than 200 feet (60 meters) deep and where the temperature is not too hot or cold, generally between 68° and 80° F (20° and 27° C). Coral reefs are sometimes likened to tropical rain forests because of their great variety of life-forms. In fact, coral reefs host more broad divisions of life-forms than can be found anywhere above the sea. In these blazing aquatic forests hundreds of species move like animated fragments of shattered rainbows: anemones, comb jellies, mollusks, bryozoans, brachiopods, flatworms, polychaete worms, peanut worms, sea stars, crabs, shrimps, sea squirts, and more. Much more.

Since the 1970s reef systems millions of years in the making have become stressed, damaged, or destroyed—smothered under silt, poisoned by upstream pollution, mined for road materials, blasted to extract fish. Corals can be killed by simple human contact, but the reef systems as a whole have been resilient. Still, nothing in their long history has prepared them for these new pressures.

Even if you admire fish only as fillets and enjoy water only as a drink, there is reason to be concerned about the swift decline of the reefs. Coral reefs have persisted for millions of years, through ice ages, massive storms, the shifting of continents, the rise and fall of sea levels. If these durable systems are in trouble, what about the rest of the ocean?

The fate of the oceans is our fate. The sea, after all, helps govern climate, weather, and planetary chemistry. It produces much of the oxygen in the atmosphere and yields water to clouds that replenish our lakes and rivers. All told, water accounts for more than 95 percent of the biosphere. Meddle with the ocean, and you jeopardize Earth’s life-support system.

Actions are being taken to protect some reefs as parks and sanctuaries: the Great Barrier Reef in Australia and the Florida Keys and Flower Garden Banks National Marine Sanctuaries in the United States, for example. Can we save them? With care, maybe we can. Whatever we do now, or don’t do, will seal the fate of Earth’s coral Edens—and perhaps our own fate, as well.