Myxogastria

Slime moulds are amazing living things.

They start as tiny cells. These cells eat small bits of food.

When they eat, they grow into a big slime. This slime can be very large. It can even grow as big as a rug!

The slime moves to find food. It can also move away from light. Later, it makes small bodies to hold seeds. Wind or bugs help spread these seeds. They live in many places like forests or deserts. Slime moulds are full of surprises!

Slime moulds are very special living things.

They belong to a group called Myxogastria. These organisms go through many different stages.

It starts with tiny cells called spores. These spores are very small. When they grow, they become single cells. Some move by crawling. Others use flagella, which are tiny tails, to swim.

These cells eat bacteria and fungus.

If two cells meet, they join together. This makes a large, slimy mass called a plasmodium. This mass is just one big cell. It can grow very large. One cell grew to be 5.5 square meters!

The plasmodium moves toward food. It also moves away from light.

When conditions change, the slime makes fruit bodies. These are shapes that hold more spores.

The wind or small bugs like woodlice help spread the spores to new places. Myxogastria live all over the world. You can find them in forests, deserts, or even underwater.

Slime moulds are amazing living things that change their shape often. They belong to a group called Myxogastria. This group includes many different types of species. Scientists have found between 888 and 1,500 species in this class.

They live all over the world. You can find them in open forests or even underwater. Some even live in deserts or under blankets of snow. You might see them on the bark of trees. These tree-dwelling types are called corticolous myxomycetes.

The life of a slime mould happens in several steps. It starts with tiny spores. These spores are very small, often between 5 and 24 micrometers. When a spore grows, it releases a single cell. In dry places, these cells crawl like amoebae. In wet places, they grow tiny tails called flagella to swim.

These cells eat bacteria and tiny bits of food. If two cells meet, they can join together. This creates a large, slimy mass called a plasmodium.

A plasmodium is a very special kind of single cell. It can grow to be huge. Most species are small, but some can cover a whole square metre. One cell grown in a lab reached 5.5 square metres!

This mass has many nuclei, which are the control centers of the cell. Some large masses have up to 10 million nuclei. The plasmodium can move toward food. It can also move away from light. This helps it find the best places to live and eat.

History shows us how people have studied these creatures. A Swedish scientist named Elias Magnus Fries described many slime moulds in 1829. Later, Thomas Huston Macbride introduced the family Myxogastridae in 1899. The specific name Myxogastria was used by Lindsay Shepherd Olive in 1970. The name comes from ancient Greek words. One word means "mucus" and the other means "fungus."

When conditions change, the slime mould makes fruit bodies. These are shapes that hold new spores. The mass crawls toward light to find a dry spot for this. Once the fruit bodies form, the process cannot be stopped. When they dry out, the spores are released. The wind can carry them away. Small animals like woodlice or beetles also help. They pick up spores or eat them and spread them later.

Myxogastria is a diverse class of organisms commonly known as plasmodial or acellular slime moulds. This group includes 5 orders, 14 families, 62 genera, and at least 888 species. However, recent studies suggest the number is much higher. Environmental sampling estimates there are between 1,200 and 1,500 species.

These organisms are fascinating because they transition through several distinct morphological phases. They can exist as microscopic individual cells, large slimy masses, or complex fruit bodies. Because they change shape so much, scientists sometimes struggle to classify them accurately. Some researchers even debate if they should belong to their own separate kingdom.

The life cycle begins with microscopic spores. These spores are mostly round and measure between 5 and 24 micrometers in diameter. Their surfaces are often textured with spikes, warts, or nets. When a spore germinates, it releases one to four haploid protoplasts. Depending on the moisture in the environment, these cells take different forms. In dry conditions, they become myxamoebae, which crawl along surfaces. In wet conditions, they become myxoflagellates, which use two flagella to swim.

These single cells enter the first trophic phase, or nourishment phase, where they consume bacteria and fungi.

If two compatible cells meet, they undergo zygogenesis. This is a process where the protoplasms and nuclei fuse to create a diploid zygote. This zygote then undergoes many nuclear divisions to become a large, multinucleated plasmodium.

The plasmodium marks the second trophic phase. This is a single, massive cell that absorbs nutrients through phagocytosis. It eats bacteria, protists, and even small pieces of organic material. This feeding allows the organism to grow to incredible sizes. While most are small, some can reach a surface area of one square meter. One lab-grown specimen of Physarum polycephalum even reached 5.5 square meters!

The plasmodium is a highly active living structure. It contains many nuclei, ranging from 8 in small types to 10 million in large, veined meshworks. The cell moves using a streaming cytoplasm that pulses in one direction. This allows the organism to reach speeds of up to 1,000 micrometers per second.

It also uses chemotaxis to move toward food and negative phototaxis to move away from light. If conditions become too dry or cold, the organism can form a sclerotium. This is a hardened, resistant resting state made of many macrocysts that helps it survive the winter.

When environmental triggers occur, the plasmodium begins fructification. This is the process of creating fruit bodies to produce new spores. Researchers believe changes in pH, temperature, humidity, or starvation may trigger this. During this time, the plasmodium stops eating and crawls toward light. This positive phototaxis helps it find a dry area for optimal spore spreading.

Once the process of fructification starts, it cannot be stopped. If the organism is disturbed during this time, it may produce malformed fruit bodies.

Fruit bodies come in many different shapes and structures. They can be stalked sporangia or netted structures called plasmodiocarps. Some look like pincushions, known as aethaliae. Most species use a structure called a capillitium to hold their spores. When the fruit bodies dry, the spores are released for dispersal. The wind is a primary mover, but small animals play a major role too. Woodlice, mites, and beetles can pick up spores or spread them through their waste.

The study of Myxogastria has a long history of discovery. The name comes from Ancient Greek words meaning "mucus" and "fungus." In 1829, the Swedish mycologist Elias Magnus Fries described many species as Myxogasteres. Later, Thomas Huston Macbride introduced the family Myxogastridae in 1899. The specific name Myxogastria was introduced by Lindsay Shepherd Olive in 1970. These discoveries have helped us understand how these unique organisms fit into the natural world. They are found everywhere from open forests to underwater, and even under blankets of snow.