Kingdom Protista Basics

Protists are eukaryotic creatures that belong to the Kingdom Protista. Protists are very varied organisms that have little in common. Protists include only eukaryotes that are not animals, plants, or fungi; they are grouped together since they do not belong to any other kingdom.

Protists are microscopic, unicellular organisms, while other organisms (such as seaweed) are vast and multicellular. A few protists (e.g., algae) are photosynthetic and thus can make their essential food, whilst some (e.g., bacteria) are heterotrophic and get their sustenance from their environment.

Characteristics of Protists

Because protists are such a varied collection of species, there are few commonalities among them. Protists, on the other hand, are all eukaryotic creatures, meaning they have nuclei and other membrane-bound organelles. In addition to mitochondria, most protists have digestive vacuoles, chloroplasts, and a cell wall.

Protists are mostly single-celled creatures, although some are multicellular. They may be found in a range of aquatic settings as well as in damp soil. Some protist species are parasites that cause illnesses including malaria, toxoplasmosis, and trypanosomiasis in humans.

Most protists reproduce asexually through budding or binary fission. Few protists, however, can create gametes and reproduce asexually.

Nutrient Acquisition in Protists

Certain protists are photosynthetic, which means they use chloroplasts to harvest sunlight for the synthesis of carbohydrates. Others are heterotrophs, such as animal-like protists and fungi-like protists. Heterotrophs search for nourishment in their environment. Which might include other microbes, carbon-rich nourishment, and decomposing biological debris.

Examples of Protists

Kingdom Protista are a diverse group of organisms with little commonality between them. Based on the qualities they share with animals, plants, and fungus, protists may be classed as animal-like, plant-like, or fungal-like.

Animal-like Protists

Protists that resemble animals are called protozoa, which means “first animal.” Because they are supposed to have developed from bacteria to become some of the earliest eukaryotes on the planet, this is the case. These early eukaryotes are thought to have given rise to all other animal life.

About all protozoa are heterotrophs, which means they get their nutrition through their environment as opposed to photosynthesis. Protozoan cells have mitochondria (for energy production) and digesting vacuoles (for the purpose of digesting).

Examples of Animal-like Protists

Protozoa are divided into four groups depending on how they move and where they live. This is the case:

• Rhizopoda
• Ciliates
• Flagellates
• Sporozoa

Rhizopoda are typically distinguished by their pseudopodia (sometimes known as “false feet”). They are cytoplasmic extensions that extend outside the cell and allow it to move about. Rhizopodia have used themselves as pseudopodia to capture microorganisms and microscopic protozoa that they then ingest and breakdown with the aid of digestive vacuoles.

Amoebas are the most common Rhizopoda. They thrive in both freshwater and saltwater environments and reproduce asexually by binary fission. Entamoeba, for example, is a parasitic amoeba that causes amoebic dysentery.

Ciliates have cilia, which are little hair-like structures that assist them in travelling through the water. Ciliates often use only their own cilia to sweep bacteria and algae through a groove that resembles a mouth on their cell membrane. In exchange, ciliates offer nourishment to larger protozoans (including amoeba).

Flagellates have appendages that resemble whips or tails, which help them move across their aquatic environments. Numerous flagellates use their flagella to capture nutrients, but they could also get nutrition from their environment. Photosynthesis allows some flagellates (phytoflagellates) to create their essential nourishment. Trypanosoma and Giardia are parasitic flagellates that may cause sleeping sickness and giardiasis.

Sporozoans are parasites that depend solely on their hosts for nutrition. There are no pseudopodia, cilia, or flagella on these protozoa. Alternatively, they use a specialised component called an apical complex to insert themselves into a target cell.

Plant-like Protists

Algae are protists that look like plants. Since they contain chloroplasts as well as chlorophyll and therefore manufacture their own food during photosynthesis, they are termed plant-like. Algae also have cellulose-based cell walls. Algae, on the other hand, lack leaves, stalks, and roots, as do genuine plants.

Algae are key producers in aquatic habitats because they are photosynthetic creatures. They are also important oxygen generators, accounting for over half of all the oxygen produced on the planet. Some algae (for example, diatoms) are single-celled organisms, whereas others (for example, seaweed) are multicellular.

Plant-like Protists Examples

Algae are divided into seven categories:

Red algae (Rhodophyta)

Algae (green algae) (Chlorophyta)

Brown algae (Phaeophyta)

Algae (yellow-green) (Xanthophyta)

Fire algae (Pyrrophyta)

Diatoms (Chrysophyta)

Euglenids (Euglenophyta)

Red algae flourish in tropical marine environments, from which they form on hard surfaces such as coral reefs. Unlike other types of algae, they lack flagella but possess cell walls. Red algae are typically unicellular, although they may also be multicellular and produce a diverse array of seaweeds.

Most green algae can be grown in freshwater, but there are a few species that likewise exist in the seas. They will be either unicellular or multicellular, but they all have chloroplasts and use photosynthesis to make their own food.

Brown algae are a kind of seaweed that may be found in a variety of forms in maritime habitats. The gigantic kelp, a brown alga that may grow up to 65 metres (215 feet) in height, is the world’s biggest sea plant.

In unicellular creatures, there are cell walls, chloroplasts, and at least one flagellum in yellow-green algae. With approximately 450-650 species recognised, they are the least frequent of all algal kinds. Yellow-green algae are most often found in freshwater, although some may also be found in saltwater and damp soil.

Dinoflagellates are another name for fire algae. Certain types of algae are bioluminescent, releasing a spooky glow at night that illuminates the ocean. Some types of red algae are capable of causing the occurrence known as “red tide” when they are present in huge quantities. Because these protists create a variety of toxic chemicals, this sort of algal bloom may represent a serious health concern.

Diatoms (also known as golden-brown algae) exist in both freshwater and saltwater and are the most prevalent unicellular algae. Diatoms are a form of plankton found in the ocean.

There are euglenids in both freshwater and saltwater. Algae contain chloroplasts and therefore can photosynthesize, but they also feed on other unicellular organisms and carbon-rich materials in their environment. Using their flagella, euglenids propel themselves throughout the water. Contrary to the majority of other algal species, Euglena lacks a cell wall. Instead, a protein-rich coating known as the pellicle surrounds them.

Fungi-like Protists

Molds are protists that look like fungi. They resemble mushrooms and thrive in moist conditions, absorbing nourishment from decomposing organic matter. They proliferate by spores and get cell walls. Their cell membranes, on the other hand, are built of cellulose, while the cell walls of fungus consist of chitin.

Examples of Fungi-like Protists

Fungi-like protists are divided into two categories:

• Molds for slime
• Molds in water

On compost piles and decaying wood, slime moulds are most often seen, where they wander about slowly in search of decomposing organic waste. When nourishment is limited, a blob-like mass forms when multiple single cells swarm together.

Surface water and damp soil are common habitats for water moulds. Water mould may be plant infections or parasitic on fish and other aquatic creatures.