Kingdom Protista – Class 11 | Chapter – 2 | Short Notes Series PDF

The kingdom Protista was proposed by Ernst Haeckel in 1866 to include all the one-celled organisms. As originally proposed, it included both prokaryotic and eukaryotic organisms. The former comprised the subkingdom Monera, whereas the latter, the sub Kingdom Protista, a name proposed by Hogg in 1860. The name “Protista” means, literally, “very first”, because Haeckel had concluded that protists were the first organisms on Earth.

Scientists speculate that protists form a link between plants, animals and fungi as these three kingdoms diverged from a common protist-like ancestor, billions of years ago. Though this “protists-like” ancestor is a hypothetical organism, we can trace some genes found in modern animals and plants to these ancient organisms.

Therefore, these organisms are traditionally considered the first eukaryotic forms of life and a predecessor to plants, animals and fungi.

Kingdom Protista

Background Information on Kingdom Protista

The classification of five kingdoms was given by Robert Whittaker in 1969, and the Kingdom Protista was a part of those five kingdoms. During that time, protists were regarded as unicellular eukaryotic organisms. But with time, the kingdom Protista expanded and even multicellular organisms found their place in that kingdom.

A special characteristic of the organisms grouped under this kingdom is that all of those organisms have a simplified cellular structure devoid of extraneous tissues and organs. The number of protists that have been discovered ranges from approximately more than 200,000. In fact, a huge number of protists are yet to be discovered beside the already-discovered humongous number of protists.

Since protists are aquatic organisms, they form their habitat mostly in watery areas. They form the foundational structure of the ecosystem by being the dominant producers. In addition to that, protists come in multifarious sizes ranging from minuscule organisms to humongous seaweeds that are capable of growing approximately 200 feet in height.

Economic Importance of Protists

  • Protists serve as the foundation of the food chain.
  • Protists are symbionts – having a close relationship between two species in which, one is benefited.
  • Some protists also produce oxygen and may be used to produce biofuel.
  • Protists are the primary sources of food for many animals.
  • In some rare cases, Protists are harvested by humans for food and other industrial applications.
  • Phytoplankton is one of the sole food sources for whales
  • Seaweed is an alga, which is considered a plant-like protist.
  • Zooplankton is fed on by various sea creatures including shrimp and larval crabs.

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By Team Learning Mantras