Rhizaria

These tiny things live in soil and water.

Some are very small. Others can grow quite long. They can form big groups.

Most of them cannot make food from light. But some have tiny plants inside them. These plants help them live. Many build hard shells to stay safe. These shells can be made of minerals. They use long, thin arms to catch food. This helps them eat small things. These tiny life forms are very important to our world.

Rhizaria are a large group of tiny living things. Most are made of only one cell. They are often amoeboids. This means they look like blobs that move. They use long, thin arms to move and eat. We call these arms pseudopods.

Most Rhizaria do not make food from sunlight. However, some live with tiny algae. The algae help them live. This helps the ocean stay healthy. Some members can grow quite large. Some can be more than one centimeter long. They can even form long colonies. These colonies can be over one meter long!

Many Rhizaria build hard shells to protect themselves. These shells are called thecae. They can be made of minerals like calcite or opal. There are three main groups in this family. Cercozoa live in soil. Foraminifera live on the ocean floor. Radiolaria float in the ocean.

Scientists use DNA to study how they are related. This helps them see how these tiny life forms grew over time.

Rhizaria is a huge group of tiny living things. Most of them are made of just one cell. These creatures are mostly amoeboids, which means they look like moving blobs. They use long, thin arms called pseudopods to move around. These arms can be thin or shaped like a net. Some rhizarians even build hard shells called thecae to stay safe. These shells are made of minerals like calcite, opal, or celestite.

These tiny life forms have many ways to get food. Most of them do not use sunlight to make food. Instead, they capture and swallow prey using their pseudopods. Some rhizarians live with tiny algae in a special partnership. This is called a symbiotic relationship. The algae help the rhizarians live. These partnerships help produce a lot of energy in the ocean.

People have noticed these organisms for a long time. In 1861, a zoologist named William B. Carpenter studied them. He grouped some together because they had similar thin arms. The name Rhizaria was later used by Cavalier-Smith in 2002. He used this name for a much larger group. Scientists used to think many were animals. Now, they use DNA to see how they are related.

There are three main groups in the Rhizaria family. The first group is Cercozoa, which are often found in soil. The second group is Foraminifera, which live on the ocean floor. They make very pretty, complex shells. The third group is Radiolaria, which float in the ocean. Some species can grow larger than one centimeter. Some even form long colonies that are over one meter long.

Rhizaria are part of a large group called the SAR supergroup. This group includes Stramenopiles and Alveolates. Scientists found these connections by looking at tiny parts of cells. They also use advanced microscopes to see them clearly. Studying their DNA helps us understand their history. We can see how they changed over a very long time. They are a very important part of our world.

Rhizaria is a massive and diverse group of single-celled organisms known as eukaryotes. Most members are amoeboids, which means they move and feed like tiny, shapeless blobs. They are defined by their use of pseudopods, which are thin extensions of their bodies. These pseudopods can be filose, meaning they are thread-like. They can also be reticulose, forming a net-like structure. Some even have microtubule-supported axopods to help them function.

While they lack a single unique physical trait to define them, they are a vital part of the ocean's biology. They help drive primary production through special partnerships with algae.

To survive, most Rhizaria use their pseudopods to capture and engulf prey. This process allows them to eat other tiny organisms. While most are non-photosynthetic, some members have formed symbiotic relationships with unicellular algae. In these partnerships, the algae live inside the Rhizaria. This relationship is very important for the ocean's energy cycle. A few specific groups, like the chlorarachniophytes, can actually perform photosynthesis themselves. This allows them to create food using sunlight.

Scientists divide Rhizaria into three main phyla: Cercozoa, Endomyxa, and Retaria. The Cercozoa include various amoebae and flagellates. These are often found in soil and typically use filose pseudopods. The Foraminifera are part of the Retaria phylum and live mostly on the ocean floor. They are known for creating intricate, complex shells called thecae or loricas. These shells can be made from minerals like calcite, celestite, or opal.

The third main group is the Radiolaria. These are amoeboids that use axopods and usually float as plankton in the ocean.

Some Rhizaria are much larger than the typical single cell. Certain species can grow to be more than one centimeter in size. Some even form massive cylindrical colonies. These colonies can reach a diameter of 1 cm. They can also grow to be longer than 1 meter.

Within the group, there are also specialized members like the Ascetosporea. These include the Phytomyxea, which parasitize plants. They also include the Mikrocytida, which are parasites of oysters. One specific species, Mikrocytos mackini, causes Denman Island Disease. This organism is very small, measuring only 2 to 3 micrometers in diameter.

Our understanding of these organisms has changed significantly over time. In 1861, the zoologist William B. Carpenter proposed the order Reticularia. He noticed that Foraminifera and Gromiida had very similar reticulose pseudopodia. He saw granules circulating inside these thin arms. However, the idea that they all belonged to one large group is a recent discovery. In 2002, the scientist Thomas Cavalier-Smith introduced the name "Rhizaria." He expanded the group to include the centrohelids and Apusozoa. Modern scientists now use molecular phylogenetics to study their DNA. This helps them map out exactly how these creatures are related.

Rhizaria are part of a much larger biological grouping called the SAR supergroup. This supergroup includes Stramenopiles and Alveolates. The connection between these groups was first suggested in 1993. Researchers noticed similarities in their mitochondrial morphologies, which are the structures used for energy. Today, the SAR supergroup is placed within a larger category called Diaphoretickes. This larger group also includes Archaeplastida and Cryptista. Because they share a common ancestor, Rhizaria is considered a monophyletic group. This means all members of the group descended from a single common ancestor.

Understanding the life cycles of Rhizaria provides even more detail. Foraminifera and Gromia have demonstrated complete sexual life cycles. In Foraminifera, the process is quite complex. They use meiosis, a type of cell division, to produce gametes. These gametes are produced at separate stages of their life. Scientists have also seen evidence of karyogamy, which is the fusion of cell nuclei, in other lineages. This includes the Euglyphida and the Thecofilosea. These biological processes help ensure the survival and diversity of the Rhizaria across the planet.