What Have We Learned About Plankton?

What exactly are plankton?

Plankton are microscopic organisms that drift on the oceans' currents. They include organisms such as diatoms, dinoflagillates, and cope pods. They also include the microscopic larva of crustaceans, sea urchins, and fish. Due to its diversity, plankton may be primitive unicellular organisms such as algae or fungi or they can become complex multicellular plants and animals such as sponges and fish.

Plankton are also found in numerous numbers of "photosynthetic" organisms that are very productive. These types of plankton are mostly responsible for generating the earth's oxygen (80%).

THEY PRODUCE MORE OXYGEN THAN ANY OTHER PLANT KNOWN TO EARTH!












 

Plankton are divided into two different groups; plant (phytoplankton) and animal (zooplankton).

Phytoplankton

Zooplankton

Phytoplankton need light like normal plants do so they are found near the surface where light is available for photosynthesis. Zooplankton, need to be near the the surface of the water too however this is so they can feed on the phytoplankton.

Because they need to be near the surface, plankton have developed several ways of floating or controlling their position in the sea. These include:

• Spikes= Help distribute the organism's weight over a large surface area, slowing its sinking.
• Examples= Zoea and the Brachiolaria Larvae both have spikes.

• Oil distribution= Oil is lighter than water, in turn allows the organism to float.
• Examples= Copepods and Diatoms produce oil to help them float.

• Air-filled floats= The float acts as a balancing agent to help keep the organism "floating" freely as they move across the ocean.
• Examples= Portuguese man-o-war uses its air-filled float to help keep it afloat. 

• 

  Portuguese man-o-war

  

  Diatoms

  

  Zoea

Plankton can also divided into two groups: Holoplankton and Meroplankton.

• Meroplankton= Found in coastal waters, they stay as plankton for their larval or early stages of life and then they either become nekton or benthos. (Example of nekton= flounder, tuna, shark. Example of benthos= worms, barnacles, algae.)
• Holoplankton= Found in open water, predominant in floating state, remain planktonic state their entire life cycle.