More Algae

The open ocean is surprisingly barren to the naked eye. Every now and again you will encounter a school of fish and their attendant predators, but most of the life that you find is gathered around...
A diet of algae and seagrasses gives this turtle ( Chelonia mydas ) greenish colored fat—and its name. Weighing as much as 500 pounds, the threatened green sea turtle lives its life at sea, with only...
Convict surgeonfish ( Acanthurus triostegus ) are the roaming sheep of the reef but, instead of noshing on grass, they feed on algae. Their grazing helps to balance the growth of algae and coral on...
Macroscopic algae ( Ventricaria ventricosa ), also known as "bubble algae" or "sea pearl," is widespread algal species that can withstand low light. Each of the bubbles is a single cell, making it...
Broad-leaf seagrass ( Posidonia australis ) with algae epiphytes grows at Corner Inlet Marine National Park in Australia . The marine park protects large areas of seagrass habitat from fishing—but it...
What are corals? Corals themselves are animals. But tropical reef-building corals have tiny plant-like organisms living in their tissue. The corals couldn’t survive without these microscopic algae–...
“Sea grapes” may sound like something Poseidon would snack on, and not a killer algae. Yet Caulerpa racemosa var. cylindracea poses a serious threat to marine life. Spread by the bilge water of boats...
In this close-up photo, you can actually see the photosynthetic algae, or zooxanthellae, living inside a tiny coral polyp. Look for the brownish-green specks in the colorless polyp. Corals depend on...
Algae has overtaken this coral reef off heavily populated Kiritimati, or Christmas Island. Few fish swim in the murky waters. The causes include pollution, overfishing, and increased water...
Around 100 million years ago, grass from land adapted to live and reproduce while submerged in seawater—the modern-day seagrasses. This sea invasion by land plants happened four separate times,...
"Fronds of giant kelp, buoyed by their gas-filled pneumatocysts, wave like pennants in the current of Monterey Bay, California," wrote George Cathcart of his image , a winning selection in the...
Since the dawn of seafaring, humankind has had to deal with the pesky creatures that settle on ships—seaweeds, barnacles, and others that take advantage of the empty real estate provided by a clean...
The sargassum fish ( Histrio histrio ) is a member of the frogfish family (Antennariidae) and typically lives in open waters near floating sargassum seaweed, which offers camouflage. Although capable...
A strain of this green seaweed, native to the Indian and Pacific Oceans, escaped public and private aquariums in California, Japan, Australia, and Monaco. It has spread widely in the Mediterranean,...
Unlike the green, leafy algae we're used to seeing on the seafloor, coralline algae has a hard crust—which you can see here at the molecular level in a photo from a scanning electron microscope. Each...
Regardless of what continent you live on, the waters that surround it are home to marine invaders. The ocean is teeming with plants and animals willing and able to move beyond their native habitats...
Closest to the seeps, where the pH is lowest and the water is most acidic, corals no longer grow. Instead there are sand, rubble and seagrasses that are able to survive. Read more about how reef...
Seagrasses growing on the seafloor of the Chesapeake Bay rely on light to grow—but, thanks to pollution, that sunlight has become more scarce. Nutrient runoff from fertilizers causes microscopic...
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