Marine Plants in the Pelagic Zone

• Kelp beds provide essential shelter for fish in the open ocean. Paul Souders/Photodisc/Getty Images

  The pelagic zone of the ocean is one of the largest zones of water. This zone refers to any body of marine water not quite near the seabed and typically encompasses the open ocean; the name even means "open sea." The pelagic zone not only contains an extremely vast array of fish and sea mammals like whales, but also a wide variety of marine plants. Plants thrive in what's known as the epipelagic zone, an area of water which can be penetrated by the surface sunlight.

Phytoplankton

• Phytoplankton are very basic organisms that may be composed of only a few cells (one-celled phytoplankton are referred to as diatoms). These tiny plants drift by the thousands or even millions, carried along by the currents in enormous clouds. They are fed upon by small fish and crustaceans and provide one of the most basic elements of the oceanic food chain. Occasionally larger fish feed off of the plankton swarms, as well, like Whale sharks or Manta rays, which swoop down into the plankton clouds with open mouths.

Dinoflagellates

• Dinoflagellates are microscopic algae that are composed of one cell and swim along using muscular tails known as flagella, hence their name. These cells can be toxic in swarms and are responsible for isolated spots of red, cloudy water known as "red tides." Shellfish are often inedible after living in areas with large numbers of dinoflagellates.

Kelp

• Kelp and other seaweeds are large, floating plants that drift in the currents, usually right atop the water's surface or right below it. Kelp beds can be enormous and provide a safe haven for many species of fish and plankton. A single strand of kelp can grow to over a hundred feet in length and create dazzling underwater forests along coastlines.