colloid. 1  a solid, liquid, or gaseous substance made up of very small, insoluble particles (as single large molecules or masses of smaller molecules) that remain in suspension in a surrounding solid, liquid, or gaseous medium of different matter.
Nekton. Nekton are the animals that can move by themselves in the ocean waters. Nekton live in all zones of the ocean. However, just like benthos and plankton, most live in the sunlight zone or shallow twilight zone since there is the most sunlight and it is easy to feed on smaller organisms such as krill and minnows.
Plankton occupy the pelagic zone of the water column, which is named after its pelagic inhabitants. Plankton may range in size from less than 2 micrometers to organisms larger than 200 micrometers. The category includes many different species of organisms in ocean and freshwater ecosystems. Plankton are divided into phytoplankton and zooplankton. Phytoplankton are photosynthetic and act as the primary producers in an aquatic environment. Zooplankton are heterotrophic and consume smaller plankton. Phytoplankton