ABSTRACT
The oceans are a habitat for various forms of life, ranging from the largest organisms anywhere on Earth to the smallest. The fauna includes various vertebrates (mammals, birds, reptiles, and sh) as well as a wide range of invertebrates. The fl ora includes the algae-from the macroscopic kelps to the small unicellular forms. The plankton includes the oating biota. The phytoplankton includes free- oating algae such as diatoms and dino agellates, and the zooplankton includes the free- oating microscopic protozoa and invertebrates. The bacterioplankton consists of free, unattached bacterial forms that include some kinds of cyanobacteria. In considering the ecology of the oceans, cyanobacteria, which are prokaryotes, have often been considered as the true algae, which, however, are eukaryotes.
