More Algae

Giant kelp ( Macrocystis pyrifera ) is large, brown algae that grows in dense forests along coasts around the world. Long stalks anchor each plant to the seafloor, and they grow meters high like...
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...
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,...
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–...
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...
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...
Macroscopic Algae ( Acetabularia crenulata ). More about mangrove ecosystems can be found in the Mangroves section .
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...
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...
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...
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...
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...
Often it's the tiniest organisms that do the most harm. One example is microscopic algae, which can grow rapidly to form harmful algal blooms . Such blooms (some are called "red tides") create...
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,...
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...
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...
Subscribe to Algae