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...
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...
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...
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...
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...
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...
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...
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...
"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...
Munch, munch. The queen parrotfish ( Scarus vetula ) scrapes algae from Caribbean coral reefs with its parrot-like beak. While feeding, hard stone and coral inevitably get mixed into its lunch, which...
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...
Macroscopic Algae ( Acetabularia crenulata ). More about mangrove ecosystems can be found in the Mangroves section .
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...
Algae, like all organisms, normally grow in balance with their ecosystems, limited by the amount of nutrients in the water. But sometimes, certain species of algae reproduce so rapidly that they...
Many species of pink coralline algae cover a reef surface in the Southern Line Islands. Often unnoticed, these pink algae crusts help to cement coral reefs together, providing extra support and...
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...
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–...
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...
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