How many nematodes live in the world?

Nematodes, or roundworms, are incredibly abundant and diverse, with estimates suggesting there are about 1 million to 1 billion individual nematodes per square meter of soil in many ecosystems. Globally, it is estimated that there could be trillions of nematodes, with over 25,000 species identified and many more yet to be discovered. They inhabit a variety of environments, including marine, freshwater, and terrestrial ecosystems, making them one of the most successful groups of multicellular organisms on Earth.