Nematodes - The most common animal on earth

Around 80% of all animals on the planet are microscopic worms called nematodes, more commonly known as Roundworms. In fact, if you go outside and take a teaspoon of soil you will have caught about 50 of them. However, these tiny organisms are not just present in the soil, but can also be found in aquatic habitats, in moss, on trees and rocks, and almost all other places on the entire planet, from deep oceans, to high mountains.

Nematodes can be found on all continents. Free-living species can feed on many different things depending on species like algae, fungus and bacteria. When nematodes eat bacteria they break down complex molecules which release nutrients back into nature in a form that plants can benefit from. So most free living species are good for plant life, nature, and in turn us.

However, even though most free living nematodes aid in the natural nutrient recycling, some species are parasites and feed on the blood of the host or the content of the intestines. More than 30 species are known to be human parasites and maybe you already know the pinworm and whipworm which are common infections. Most free-living species are less than two millimeters in size, but some of the human parasites can be more than 30 centimeters, and other species are even larger.

One of the human parasitic nematodes is called Ascaris lumbricoides. An infection with this parasite is so common that some estimates suggest that as much as 1 billion (yes billion) people in the world are currently infected. The vast majority of the cases occur in warmer parts of the world like South America, Africa and Asia.