Diatom algae: what they are, characteristics and what they are for

Diatoms are microscopic unicellular algae of the division Chrysophyta, class Bacillariophyceae, which inhabit aquatic, terrestrial and humid environments, and in various environmental conditions, from polar waters to tropical regions. These algae have a very ornate crystal structure composed of silica (called a frustule), which is divided into two parts that fit together perfectly, similar to a Petri dish. They are found throughout the world and are responsible for approximately 20% of terrestrial oxygen, and are also essential in the aquatic food chain.

Diatoms measure between 20 and 300 microns, although some reach more than a millimeter. Their silica shell has small pores that allow them to absorb nutrients and secrete polysaccharides. They contain chlorophyll, ß-carotene and fucoxanthin, which allows them to carry out photosynthesis.

• Diatoms have yellow-brown chloroplasts with pigments such as β-carotene, fucoxanthin and diatoxanthin, and they store food in the form of carbohydrates or oils, which also helps them stay afloat.
• Diatoms reproduce asexually by cell division, but their size decreases with each generation. Eventually, they reproduce sexually, forming a zygote (auxospore) that grows and restores the cell’s original size.
• Although diatoms are generally not motile, some species can move by raphe contraction, and regulate their buoyancy with intracellular lipids. This allows them to stay in surface waters where they receive more light.

• Natural fertilizer: Diatomaceous earth is an excellent fertilizer, rich in essential nutrients for plant growth and improves soil fertility.
• Effective insecticide: Diatom powder dehydrates and punctures the exoskeleton of insects, killing them progressively, without affecting larger living beings.
• Soil improver: Used to neutralize the toxicity of heavy metals and improve contaminated soils, especially in areas affected by hydrocarbons or heavy metals.
• Biodiesel: The high concentration of lipids in diatoms facilitates the production of biodiesel, contributing to the creation of more sustainable biofuels.
• CO₂ Reduction: Diatoms capture carbon dioxide and convert it to oxygen through photosynthesis.
• Environmental indicators: Diatoms are used to study water quality and climate changes, since they are sensitive to the environmental conditions of the water. Here you can learn more about Environmental Indicators or bioindicators: what they are, types, examples and importance.

Diatoms have a unique cellular structure made up of a thick, rigid silica wall, known as a frustule. This frustule is composed of two unequal valves that overlap, a lid called the epivalve and a base called the hypovalve, joined by a belt.

The valves have perforations called areolas, arranged in grooves, which allow the exchange of substances with the environment. Additionally, diatoms have structures such as the central nodule, the raphe (a crack in the valves) and the polar nodule. These characteristics, together with the ornamental processes on the valves, give them great diversity.

Inside the cell, there are other important components. Some of the internal parts of a diatom are: pyrenoid, plastids, mitochondria, vacuole, endoplasmic reticulum, Golgi apparatus and microtubules.

Where are diatom algae found?

They mainly live in aquatic environments, both marine and freshwater, floating in the water column or attached to surfaces.

What role do diatoms play in the ecosystem?

They are primary producers that generate oxygen and form the basis of many aquatic food chains, in addition to participating in the carbon and silicon cycle.

What is the importance of diatoms in the food chain?

They are the main food for zooplankton and other microscopic organisms, which makes them an essential link for marine and aquatic life. Here you can read about the Food Chain: what it is and examples.

Why are diatoms considered bioindicators?

Because its presence, abundance and sensitivity to contaminants make it possible to evaluate water quality and detect environmental changes or contamination.

Do diatoms carry out photosynthesis?

Yes, diatoms are photosynthetic algae that produce oxygen and obtain energy from sunlight, like plants and other algae.

How do diatoms reproduce?

Mainly by cell fission (asexual reproduction), although they can also reproduce sexually under certain environmental conditions.

What is the difference between diatoms and other algae?

Diatoms have a silica frustule (cell wall) with ornate shapes, and their reproduction, pigments and habitats may differ from other algae.

What is diatomaceous earth and what is it used for?

It is a powder made from fossilized remains of diatoms. It is used as a natural fertilizer and insecticide, water filter, additive in animal feed and cosmetic product.

If you want to read more articles similar to Diatom algae: what they are, characteristics and what they are for, we recommend that you enter our Ecosystems category.