Plankton

Reasons Plankton are important:

Plankton

• They play a key role in the oceanic food web.  For example, they are the key food source for zooplankton.  Even larger fish depend on plankton in order to maintain their survival.
• Phytoplankton produces much of the Earth's oxygen supply.
• Plankton can be key indicators of ecosystem change to investigators such as scientists.

There is a big difference between diatoms and dinoflagellates. Diatoms are a part of a group called alveolates.  They are most common in marine and freshwater phytoplankton, and some are heterotrophic.  Diatoms, on the other other hand, are a part of a group called stramenopiles which are unicellular, photosynthetic algae with cell walls that contain silica.

Dinoflagellates

Diatoms