Plankton are the diverse collection of organisms that live in large bodies of water and are unable to swim against a current. They provide a crucial source of food to many large aquatic organisms, such as fish and whales. Plankton includes tiny plants and animals in both sea and fresh water that float with the tides and currents. Their name is derived from the Greek meaning "drifter" or "wanderer." There are two types of plankton. Tiny plants called phytoplankton and tiny weak swimming animals called zooplankton. Some plankton are babies that will grow into strong swimming, non-planktonic adults. Others will remain plankton for their entire lives.
Phytoplankton is made of very tiny usually one celled plants. Since plants make their own food and release oxygen as a byproduct, all the other living things in the ocean depend on them directly or indirectly for food or oxygen. Diatoms are the most common type of phytoplankton. They are single celled algae whose cell walls contain silica. The name diatom actually means "cut in two" in Greek because the actual diatom fits inside this cell wall, with one half of the wall fitting over the second half, like a lid. There are many different kinds of diatoms, and they come in a variety of shapes.
Zooplankton are tiny microscopic animals they are also known as animal plankton. These animals may spend their entire lives as plankton. Some Zooplankton can grow to be bigger in their adult lives. Zooplankton can also be categorized according to size: nannoplankton are unicellular animals that feed on phytoplankton and are in turn eaten by other zooplankton (5/1000 mm to 60/1000 mm); microplankton (60/1000 mm to one mm) are composed primarily of eggs and larvae, usually of invertebrates; macroplankton (over one mm) often contain large numbers of copepods, along with amphipods, cumaceans and arrow worms; and megaplankton include mainly the large jellyfishes and their relatives the Portuguese man-o-war and the By-the-wind sailor, which move at the mercy of the currents. Because phytoplankton make their own food using the energy of the sun (in a process called photosynthesis), they are called "producers." That places them at the very base of the food web. Many animals eat plankton directly, or feed on animals that eat plankton. Animals that eat plants or other animals are called "consumers," and bacteria that break down dead plants and animals are called "decomposers."
Phytoplankton is made of very tiny usually one celled plants. Since plants make their own food and release oxygen as a byproduct, all the other living things in the ocean depend on them directly or indirectly for food or oxygen. Diatoms are the most common type of phytoplankton. They are single celled algae whose cell walls contain silica. The name diatom actually means "cut in two" in Greek because the actual diatom fits inside this cell wall, with one half of the wall fitting over the second half, like a lid. There are many different kinds of diatoms, and they come in a variety of shapes.
Zooplankton are tiny microscopic animals they are also known as animal plankton. These animals may spend their entire lives as plankton. Some Zooplankton can grow to be bigger in their adult lives. Zooplankton can also be categorized according to size: nannoplankton are unicellular animals that feed on phytoplankton and are in turn eaten by other zooplankton (5/1000 mm to 60/1000 mm); microplankton (60/1000 mm to one mm) are composed primarily of eggs and larvae, usually of invertebrates; macroplankton (over one mm) often contain large numbers of copepods, along with amphipods, cumaceans and arrow worms; and megaplankton include mainly the large jellyfishes and their relatives the Portuguese man-o-war and the By-the-wind sailor, which move at the mercy of the currents. Because phytoplankton make their own food using the energy of the sun (in a process called photosynthesis), they are called "producers." That places them at the very base of the food web. Many animals eat plankton directly, or feed on animals that eat plankton. Animals that eat plants or other animals are called "consumers," and bacteria that break down dead plants and animals are called "decomposers."