More Algae

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...
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...
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...
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...
Seagrasses are found in shallow salty and brackish waters in many parts of the world, from the tropics to the Arctic Circle. Seagrasses are so-named because most species have long green, grass-like...
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...
In the ocean, microscopic forms of algae, known as dinoflagellates , can "bloom" into dense patches near the surface, often referred to as "red tides." Some of these harmful algal blooms (HABs) are...
Macroscopic Algae ( Acetabularia crenulata ). More about mangrove ecosystems can be found in the Mangroves section .
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...
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...
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...
Dugongs , along with manatees , make up a group of marine mammals called sirenians or seacows . In the modern world, only one species of seacow is found in any one place in the world. However, the...
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...
Corals, sponges, and algae are the major components of most coral reef communities. To the untrained eye, they are sometimes difficult to tell apart. More about coral reef ecosystems can be found in...
"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...
Stare at a tide pool and you will often see a crust of pink coating the bottom. No, this is not bubblegum from some careless teenager’s shoe: it’s a stony kind of seaweed that, like other seaweeds,...
One of the ocean's tiniest organisms often does the most harm. Microscopic algae can grow rapidly to form harmful algal blooms (sometimes called "red tides"), which create unhealthy water conditions...
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