Phytoplankton are one of the most important forms of life on the planet Earth. However, relatively little is known about them. They are basically forms of plant life that live in the ocean. Phytoplankton serve as food for a wide variety of species, mostly small fish but also some species of whales. Many different kinds of phytoplankton exist, but several characteristics can be used to broadly define what phytoplankton are.
Requirements for Life
Phytoplankton are all similar to plants in that they require sunlight, water and nutrients to survive and to grow. They also contain chlorophyll, the same pigment that makes plants green, and for that reason phytoplankton also mostly come colored green. Like plants, phytoplankton also use their chlorophyll to generate carbohydrates, which they in turn use as the building blocks necessary to grow.
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However, phytoplankton require some other minerals in addition to carbon dioxide to live. They get these other minerals, such as iron, when colder water from the lowers depths rises up to the surface of the water.
Phytoplankton almost all live near the surface of the ocean because that is where the light is the most abundant.
Phytoplankton only tend to live about a day or two before they are either eaten or they die. In colder environments, they usually "bloom" in the springtime, when the most light hits the surface of the water.
Phytoplankton cannot swim and are therefore at the mercy of the ocean currents to carry them around.
Effect on Global Temperature
Phytoplankton play a very important role in the global climate. Like onshore plants, phytoplankton take in carbon dioxide and emit oxygen during photosynthesis. Therefore, the amount of phytoplankton present in the world's oceans is very important because they can affect the amount of carbon dioxide present in the Earth's atmosphere. Carbon dioxide is a greenhouse gas, meaning that when there is less carbon dioxide in the Earth's atmosphere, the overall global temperature is lower. Therefore, phytoplankton levels can affect the Earth's overall temperature.
Indicators of Change
Phytoplankton are also important as indicators of chemical or physical or chemical changes in global waters. Phytoplankton populations are extremely vulnerable to these types of changes, and their population will increase or decrease rapidly based on them. For this reason, scientists make sure to keep very close tabs on the phytoplankton populations throughout the world because it could alert them to potential problems.