Plankton vary in size from microscopic diatoms to jellyfish that can be several feet long. Most plankton are less than an inch long. There are two main types of plankton: phytoplankton and zooplankton. Phytoplankton are marine plants. read more
Diatoms and Cyanobacteria are really pretty to look at(to me anyway) and Rotifera are cool to watch, but I this the coolest plankton are the larval stage animals the happen into a plankton tow every now and then. read more
Some plankton can travel vertically hundreds of meters in a single day. Deeper depths afford some plankton a measure of protection from predators who require light in order to hunt. Plankton organisms can be algae, bacteria, protozoa, crustaceans, mollusks and members of most phylums, according to the Encyclopaedia Britannica. read more