Cercozoa

Tiny living things live in many places. Some live in the soil. Others live in the sea.

These tiny things are just one cell. They do not have a mouth. Instead, they use tiny arms to move. They use these arms to catch food.

They like to eat tiny bacteria. This helps the tiny things in the dirt stay healthy. Some even live on plant leaves.

Some of them have small shells. These shells can be made of glass. Other ones can make nets to catch food.

It is amazing how much they do. They are very important to our world.

Cercozoa are tiny living things made of just one cell. Scientists first found them by studying their DNA. DNA is the code inside a cell. These tiny cells live in many places. They are found in soil, fresh water, and the sea.

Cercozoa do not have a mouth. Instead, they use tiny arms to catch food. These arms are called pseudopods. Some Cercozoa use thin arms called filopodia. This group is called Filose. Others make a net of arms to catch food. This group is called Reticulose.

Many Cercozoa eat bacteria. This helps keep the balance of life in the dirt and on leaves. Some Cercozoa even live in animal feces. They use it for food or to travel. Some types, like Euglyphids, make shells from silica. Silica is a material like glass. Other types, called Chlorarachniophytes, have chloroplasts. These are tiny parts that help them use light. Scientists study them to learn how cells grow.

Cercozoa are a huge group of tiny, single-celled living things. Scientists call them eukaryotes because their cells have special parts inside. These tiny creatures are very important to our world. They live in soil, fresh water, and the salty ocean. Many of them are natural predators of bacteria. This means they hunt and eat bacteria to stay alive. They help keep the balance of life in many different places.

These tiny cells move and eat in interesting ways. They do not have a real mouth like many other microbes. Instead, they use parts of their body called pseudopods to catch food. Some use thin, thread-like arms called filopodia. This way of moving is called being "filose." Other types make a net of arms to catch prey. This net-like way of moving is called being "reticulose."

Scientists learned about Cercozoa in a new way. Usually, researchers look at how cells look under a microscope. But Cercozoa are hard to group by how they look. Instead, scientists used molecular phylogeny to study them. This means they looked at the tiny codes inside the cells, like rRNA. This helped them see how the different groups are truly related. They are part of a larger group called Rhizaria.

There are many different kinds of Cercozoa with unique facts. Euglyphids are filose amoebae that build shells from silica. Silica is a material often used to make glass. Some live in soil or on aquatic plants. Chlorarachniophytes are very special because they have chloroplasts. These help them use light, and they even have a tiny leftover nucleus. In forest soils, these microbes can make up 40% to 60% of all protozoan RNA.

Cercozoa are found in almost every corner of nature. Some live on the leaves of plants in a place called the phyllosphere. They eat certain bacteria, which changes which bacteria live on the leaf. Other types are coprophilic, which means they love to live in animal feces. They use it for food or to travel through an animal host. This makes feces a very important home for many new species. From the deep ocean floor to your backyard, they are everywhere.

Cercozoa is a large phylum of single-celled eukaryotes. These organisms are incredibly diverse in their shapes and how they live. They are part of a larger supergroup called Rhizaria. Cercozoa are closely related to the phylum Retaria, which includes amoeboids with complex shells. Unlike many other microscopic groups, Cercozoa are difficult to define by how they look under a microscope. Instead, scientists group them using molecular phylogeny. This is the study of evolutionary relationships using genetic material like rRNA, actin, or polyubiquitin. They play a vital role in ecosystems by acting as natural predators of many bacteria.

To eat and move, most cercozoans use specialized structures called pseudopods. These are temporary extensions of the cell body. Interestingly, these organisms lack a true cytostome, which is a permanent mouth found in many other protozoa. Instead, they rely on the behavior of their cytoskeleton to capture prey. Scientists divide them into two main groups based on this movement. The first group is the filose cercozoans. These use filopodia, which are thin, thread-like pseudopods. The second group is the reticulose cercozoans. These organisms form a reticulating net of pseudopods to trap food.

Within these groups, you can find many distinct types of life. Filose amoebae include the Euglyphids, which build shells from siliceous scales or plates. These are often found in soil or on aquatic plants. Another example is the Gromia, which is also a shelled amoeba. Tectofilosids are another type of filose amoeba that produces organic shells. In the reticulose group, the Chlorarachniophytes are particularly famous. They possess chloroplasts, which are parts used for photosynthesis, bound by four membranes. They even contain a vestigial nucleus called a nucleomorph. This makes them important for studying how organelles originated through endosymbiosis.

The history of how we classify Cercozoa is a story of changing technology. Originally, scientists thought Cercozoa included both the Filosa and Endomyxa groups. They used ribosomal RNA and tubulin to make these early guesses. However, later multigene phylogenetic analyses showed that the group was paraphyletic. This means it did not include all the descendants of a common ancestor. Because of this, Endomyxa was moved, and Cercozoa became a synonym for Filosa. More recent phylogenomic studies with better sampling have changed things again. They have recovered a sister relationship between Filosa and Endomyxa. Today, modern classification usually keeps Endomyxa, Cercozoa, and Retaria as three separate phyla.

Cercozoa are found in massive numbers across the planet. They are among the most abundant protozoa in soil, marine, and freshwater habitats. In temperate soils, they are a dominant group of free-living microorganisms. They account for about 30% of identifiable protozoan DNA in arid or semi-arid soils. In more humid soils, they make up 15% of the DNA. When scientists look at RNA in forest and grassland soils, Cercozoa represent 40% to 60% of all identifiable protozoan RNA. In the ocean, they make up between 9% and 24% of all operational taxonomic units found on the seafloor.

Some cercozoans have very specific and surprising lifestyles. Many are coprophilic or coprozoic, meaning they use animal feces for nutrients or transport. This makes feces a major, though understudied, reservoir of microbial diversity. Many new lineages, especially among the sarcomonads, are discovered this way. Other cercozoans live in the phyllosphere, which is the surface of plant leaves. Sarcomonads are perfectly adapted to this environment because they can form cysts. They can feed and multiply within just a few hours. By eating bacteria, they actually change the bacterial community on the leaf. They reduce populations of alphaproteobacteria and betaproteobacteria while favoring gammaproteobacteria.

The internal structure of the phylum is organized into complex branches. The subphylum Monadofilosa is considered a robust clade. It includes groups like the Metromonadea and the Helkesea. These two together form the paraphyletic Eoglissa. Below them is the clade Ventrifilosa, which contains the Imbricatea, Sarcomonadea, and Thecofilosea. The other subphylum is Reticulofilosa. This group is likely paraphyletic. It includes the Granofilosea and the Chlorarachnea. Recent studies also identify newer orders like Tremulida and Aquavolonida. These are currently classified within the class Skiomonadea inside the Reticulofilosa subphylum.