More 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...
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...
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–...
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...
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...
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...
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...
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,...
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,...
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 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...
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...
Macroscopic Algae ( Acetabularia crenulata ). More about mangrove ecosystems can be found in the Mangroves section .
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,...
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...
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...
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...
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...
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