Protist Kingdom

Protozoa and algae belong to this kingdom . In the past, these organisms were grouped in the Animal and Vegetal kingdoms, respectively. Nowadays, we know that they are part of the protists due to particular characteristics. The representatives of this realm are eukaryotic, single-celled or multicellular, autotrophic or heterotrophic individuals.

They are found in the soil or in aquatic environments , and may be free-living, parasitic or associated with other beings, such as corals.

Protists have a role of great environmental importance, being responsible for the population control of bacteria , for the cycling of nutrients and photosynthesizers , for the synthesis of much of the global primary productivity. Most species are aerobic, but there are also optional and strict anaerobic species.

Algae Classification

The brown algae are multicellular and marine, reaching a large size (Photo: depositphotos)

The word algae refers to photosynthetic autotrophic organisms, unicellular or multicellular, found in humid, freshwater or saltwater environments. The group of algae is very diverse and their classification is based on the type of pigment, type of chlorophyll, whether they are unicellular or multicellular, among other characteristics.

Diatoms : they are single-celled and are found in cold waters. Its cells are covered by a carapace, with different shapes and colors. They are important components of phytoplankton, serving as food for many organisms.

Red Algae : known as rhodophytes, have a reddish color due to the presence of a pigment called phycobilin, they are multicellular, found in fresh or salt water.

See also:  Fungi Kingdom

Green Algae: known as chlorophytes, have a green color due to the presence of chlorophyll. They can be single or multicellular, fresh or salt water, or even live on damp trunks and associated with fungi, forming lichens.

Pardas Algae : known as phaeophytes, have a brown color due to the presence of fucoxanthin. They are multicellular and marine, and can reach a large size in length.

Euglenoids: they are flagellated, single-celled, freshwater or saltwater organisms. They are indicators of water quality, as they are abundant in polluted water environments, with excess nutrients.

Dinoflagellates : they are organisms with two flagella, unicellular, autotrophic or heterotrophic. Some are bioluminescent, that is, they can generate light through chemical reactions. Some species also have reddish pigments and produce toxins, a phenomenon known as the red tide.

Classification of Protozoa

Rhizopods : Also known as Sarcodines, they are organisms that have pseudopods (extensions of the cytoplasm with function of locomotion and feeding).

Ciliates : They are characterized by the presence of cilia, used for locomotion, displacement of the organism in aquatic environments and in food (moving particles of food to the cell).

See also :  Reino Plantae

Flagellates : They are individuals who have flagella, long filamentous structures, used in the movement and capture of food.

Foraminifera : The organisms of this group have an external carapace with perforations through which the pseudopods used in food capture, locomotion and attachment to substrates are projected.

Sporozoa: They are parasitic, single-celled, without locomotion structures.

Curiosities about protists 

Most protozoa are parasites of other organisms and cause disease. Among them we can mention: Amebiasis, cutaneous Leishmaniasis, Trichominiasis, Chagas’ Diseases, Malaria and Toxoplasmosis.

See also :  Kingdom Monera – Characteristics of bacteria

In contrast, many algae and protozoa make up plankton and are extremely important in the environment, as they form the basis of the aquatic food chain, that is, they serve as food for other organisms and in the case of algae, essential in the photosynthetic process. Protists are also important in the economy, as they are used in food (sushi made with dry nori seaweed), in the pharmaceutical and cosmetic industry.

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