Are Protists Photosynthetic? 7 Facts (Read This First!)

In this article, we get know about 7 Important Facts regarding ‘Are Protists Photosynthetic?’, along with their characteristics, functions and examples.

Protists can perform photosynthesis. Planktons fix over half of the carbon dioxide in the atmosphere. All unicellular eukaryotic creatures are classified as protists. They can be categorised as being similar to plants (autotrophs), fungus (saprotrophs), or animals (paratrophs) (heterotrophs). Protists that resemble plants carry out autotrophic photosynthesis.

Protists that use photosynthetic processes include dinoflagellates, euglena, and diatoms.

Let us discuss some facts –

Are all protists photosynthetic?

Are some protists photosynthetic?

What type of protists are photosynthetic?

What type of protists are non-photosynthetic?

Photosynthetic protists characteristics

Which protist is photosynthetic?

Non-photosynthetic protist examples

Characteristics of Protists

Protists are similar to one another in a number of ways.

  • They have a nucleus since they are eukaryotic organisms.
  • A majority have mitochondria.
  • They might also be parasites.
  • They all favour damp or aquatic conditions.

Classification of Protists

For classification, the protists are divided into three groups:

  1. Heterotrophic protists with animal-like characteristics which can move.
  2. Autotrophic, photosynthesizing protists that resemble plants.
  3. Heterotrophic protists that resemble fungi; they have cells with cell walls and reproduce by spore formation.

However, keep in mind that protists are not fungi, plants, or mammals.

Are all protists photosynthetic?

Protists are not all phototrophs. Some organisms are mixotrophs, whereas others are heterotrophs. Phytoplankton includes dinoflagellates, chrysophytes, and euglena, which are photosynthetic Protista that mostly inhabits freshwater and oceans. Some protozoans, such as sporozoans, sarcodines, flagellates, and ciliates, are parasitic protists living off dead and decaying organic substances like slime mold.

The unicellular eukaryotes known as protozoa are primarily found in water. Its character is reminiscent of mushrooms, animals, and plants. Most parasites, or phytoplankton, are photosynthetic organisms living in lakes and oceans. Their environment influences the way they feed.

Key features

  • The Protista are unicellular, eukaryotic organisms that are phylogenetically related to eukaryotes. Protists’ modes of diet are influenced by their habitat and nature. Photosynthetic protists are autotrophic, which means they make their own nutrition like plants.
  • It has various divisions and primarily comprises algae, which range in size from tiny unicellular organisms to massive seaweed.
  • Polyphyletic or paraphyletic algae are seen in photosynthetic protists. While paraphyletic protists exhibit common ancestors, some have unusual forebears and belong to the polyphyletic category.
  • Although algae are categorized as monophyletic, in general, they do not belong there because they do not share recent ancestors with birds and reptiles.
  • Since chloroplasts are found in photosynthetic protists, which undergo photosynthesis similarly to plants, they are able to repair 80% of carbon dioxide.
  • Plants, algae, and cyanobacteria all engage in oxygenic photosynthesis, which is carried out through the Calvin cycle, it successively fixes carbon and carbon dioxide using ATP and NADPH.
are protists photosynthetic
Tree of life’s phylogeny and symbiogeny, illuminating the emergence of protists from Wikipedia

Are some protists photosynthetic?

All unicellular eukaryotic organisms are considered protozoa. They are divided into groups that resemble plants (autotrophs), fungus (saprotrophs), or animals (saprotrophs) (heterotrophs). Protists that resemble plants are autotrophic and engage in photosynthesis. Protists that use photosynthetic processes include dinoflagellates, euglena, and diatoms.

are protists photosynthetic
Illustration of a single cell in vector form. Euglena viridis, Paramecium caudatum, and Amoeba proteus. Protozoa from Wikipedia
  • These have flagella for movement and are unicellular.
  • Photosynthetic protists are eukaryotic organisms that produce their own food and mostly contain chloroplast.
  • Protists that carryout photosynthesis include dinoflagellates, euglenoids, and diatoms.

What type of protists are photosynthetic?

Eukaryotes include protists. They only have one cell. They live in environments that are both moist and saline. Protists include algae, euglena, diatoms, and paramecium, for instance. They are separated into protists that resemble animals, plants, and fungi.

Ex:

Protists that use photosynthetic processes resemble plants. Through photosynthesis and sunlight, they receive their food and energy. Chloroplasts are present.

  • Nuclear membranes surround DNA in protists. They have additional membrane-bound organelles as well.
  • The majority of protists can migrate, and many of them live in watery habitats.
  • Protists can reproduce naturally or vegetatively and have complicated life cycles.
  • Protists use photosynthesis to ingest, absorb, or synthesize food.

What type of protists are non-photosynthetic?

Ciliates and flagellates are not photosynthetic. Polyphyletic protists are readily divided into two groups depending on their modes of motility: flagellates and ciliates. There are heterotrophic phagotrophs and some that are photosynthetic.

Ex:

  • Single-celled, non-photosynthetic protozoans and protozoa, including ciliates, amoebae, and flagellates, are also referred to colloquially as protozoa and protozoans.
  • Zooflagellates are tiny, colorless organisms with spherical, oval, bell-shaped, spindle-shaped, or slipper-shaped bodies. They are protoplasmically organized, acellular, or non-cellular organisms.
  • They are occasionally viewed as non-photosynthetic variations of originally photosynthesis-dependent flagellates. Flagella are specialised organelles used for movement and food engulfment.

Photosynthetic protists characteristics

Protists are eukaryotes, which implies that their DNA is housed in their nucleus. They also consist of organelles that are membrane-bound, such as the endoplasmic reticulum and mitochondria.

Most protists have just one cell. Some contain several cells. Because of the protist kingdom’s diversity, there are numerous ways for them to obtain food and reproduce.

  1. These are typically aquatic and can be found in the soil or other moist regions.
  2. The majority of protist species are unicellular creatures, although others, like kelp, are multicellular. Certain kelp species can reach heights of more than 100 feet. (Giant Kelp)
  3. Like all eukaryotes, the cells of these creatures have a nucleus and organelles that are attached to membranes.
  4. They could be autotrophic or heterotrophic in nature. An autotrophic organism may produce food for itself and persist. Contrarily, a heterotrophic organism must obtain its nutrition from other living things like plants or animals in order to survive.
  5. The individuals in this class exhibit symbiosis. For instance, the multicellular protist kelp (seaweed) offers otters safety from predators within its dense kelp. The otters then consume sea urchins, which typically consume kelp.
  6. Protists have been found to exhibit parasitism. Sleeping sickness in humans can be brought on by species like the protozoan Trypanosoma.
  7. Protists move about by using their flagella and cilia. Several Protista kingdom organisms have pseudopodia that aid in movement.
  8. Sporadic reproduction is used by protozoa. Natural reproduction is extremely uncommon and only happens under stressful conditions.

Which protist is photosynthetic?

Let us analyze the different examples given in the options:

  • Diatoms: A class of photosynthetic algae are diatoms. They are immobile and aquatic. Its skeleton is formed of siliceous material. Frustule is the name of the shell.
  • Euglenoids: These organisms are classified as protists. Both freshwater and marine environments contain them. Euglenoids are capable of photosynthesis since they have chloroplasts. These protists are photosynthetic.
  • Slime moulds: These organisms are classified as protista. It consumes decaying plant matter and the bacteria found there. It inhabits soils, woodlands, sewers, and gutters. A photosynthetic protist is not what it is.
  • Sarcodines: Some sarcodines are parasitic, whereas others are free-living. They are members of the protozoan phylum. The protists are not photosynthesis-based.
  • Dinoflagellates: Dinoflagellates are photosynthetic protists that belong to the kingdom Protista. Bioluminescence is exhibited by several species.
  • Ciliates: Ciliates are a class of protozoans. They resemble hair and are shorter than flagella but seem similar. A photosynthetic protist is not what it is.
  • Zooflagellates: These organisms are protists and are members of the kingdom Protista, but neither they nor their food is prepared by them. A non-photosynthetic protozoan.

Protists are heterotrophs because they engage in phagocytosis in addition to photosynthesis. Some are not capable of locomotion, while others do it with the aid of cilia and flagella. Reproduction is typically done sporadically.

are protists photosynthetic
A sampling of protists, composed of images from Wikipedia

Non photosynthetic protist examples

Protozoa

Protozoans are heterotrophic, occasionally parasitic, unicellular creatures that are further split into different groups based on traits like motility. These groups include the (flagellated) Flagellata, the (ciliated) Ciliophora, the (phagocytic) amoeba, and the (spore-forming) Sporozoa.

  1. Flagellata: A cell or creature containing one or more flagella, which resemble whips, is referred to as a flagellate. The term “flagellate” also refers to a specific architecture (or level of organisation) and mode of motion that are shared by numerous prokaryotes and eukaryotes.
  2. Ciliophora: The alveolates known as “ciliates” are distinguished by the presence of cilia, which resemble hairs and are structurally identical to eukaryotic flagella but are often shorter, more numerous, and have a different undulating pattern.
  3. Amoeba: An amoeba, also defined as an amoeboid, is a type of cell or single celled organism that has the ability to modify its shape, typically through expanding and contracting pseudopods.
  4. Sporozoa.: The majority of what used to be known as the Sporozoa, a class of parasitic protozoans without flagella, cilia, or pseudopods, is made up of the Apicomplexa. However, the majority of the Apicomplexa move by using a gliding mechanism..

Mold

Molds are often fungi, however slime moulds and water moulds are saprophytic (fungus-like) protists, some of which are diseases. The cellular and acellular forms of slime moulds are two different species.

  • Slime molds: A variety of unrelated eukaryotic organisms having a life cycle that includes a free-living single-celled stage and the production of spores are collectively referred to as slime mould or slime mould informally.
  • Water molds: Oomycota belongs to an unique evolutionary branch of eukaryotic microorganisms known as oomycetes, which resemble fungi. They are heterotrophic filamentous organisms that have both natural and sporadic reproduction.

For protists, is reproduction natural or sporadic?

Take note of the Paramecium’s cell division into two. This is plainly an sporadic method of reproduction. But remember that the kingdom of protists is incredibly diverse, and certain protists can reproduce naturally.

Habitats for protists 

Protists are commonly found in water. They need a moist environment in order to survive. Their natural habitats include wet areas like marshes, puddles, lakes, and the ocean. Protists can exist independently. Some people have mutually beneficial connections. Humans are just one of the creatures they reside on or inside of.

Protists’ Motility

The majority of protists can move. The capacity to move is this. Protists have three different kinds of appendages for locomotion. They might have pseudopods, flagella, cilia, or “false feet.” There may be one or several whip-like flagella.

Flagella are similar to cilia, although cilia are shorter and more numerous. They might disappear completely round the protist cell’s surface. Pseudopods are transient, cytoplasmic appendages that resemble feet.

Reproduction of protists

Protists’ life cycles are intricate. Many people can reproduce naturally and sporadically. A protist named Spirogyra, a kind of algae, serves as an illustration. It often exists as binary fission-reproducing haploid cells. Spirogyra may develop strong spores that may endure hard circumstances in a stressed environment, such as one that is extremely dry.

Protists and several other species create spores, which are reproductive cells. A diploid zygote can be created by the fusion of two protist spores that are near to one another. This kind of natural reproduction exists. The zygote subsequently proceeds through meiosis, resulting in haploid cells that carry out the cycle once more.

Nutrition of protists

One of three methods is how protists obtain nutrition. They could consume, absorb, or produce organic molecules on their own.

  • Bacteria and other small particles are eaten or swallowed by ingestive protists. By expanding their cell wall and cell membrane all around the food item, they create a food vacuole. In the vacuole, enzymes then break down the meal.
  • Protists that can absorb molecules of food cross their cell membranes. This happens by diffusion. Important decomposers, these protists.
  • Protists that can make food through photosynthetic processes do so. They are important aquatic ecosystem producers.

Conclusion

In the above article, we studied about photosynthetic and non-photosynthetic protists, and their examples with characteristics. Some other interested interesting facts about photosynthetic protists have also been studied.

Also Read: