The map above shows where you can find them, although it uses an odd colour scheme where darker means fewer nematodes and lighter means more.
But what are nematodes?
Nematodes, also known as roundworms, are a diverse phylum of worms belonging to the group Nematoda.
They are among the most numerous multicellular animals on Earth, with over 25,000 known species, though the actual number is likely much higher.
Nematodes can be found in a wide range of environments, from soil and freshwater to marine environments and even as parasites in plants, animals, and humans.
Key Characteristics of Nematodes:
Body Structure: Nematodes have a simple, unsegmented, cylindrical body that is tapered at both ends. They have a complete digestive system, meaning they have both a mouth and an anus.
Size: They range in size from microscopic (about 0.1 mm) to over 1 meter long, depending on the species.
Diverse Habitats: They are incredibly adaptable and can live in almost any environment, from deep oceans to soil, and inside hosts as parasites.
Feeding Habits: Nematodes have varied diets; some are free-living and feed on bacteria, fungi, and small invertebrates, while others are parasitic and feed on the tissues of their hosts.
Reproduction: Nematodes reproduce sexually, and some species can reproduce asexually. They lay eggs, which hatch into larvae that go through several molts before becoming adults.
Importance of Nematodes:
Ecological Role: They play a vital role in nutrient cycling and soil health by decomposing organic material and controlling populations of other microorganisms.
Agricultural Impact: Some nematodes are beneficial as biocontrol agents against pests, while others are harmful, causing significant crop damage (e.g., root-knot nematodes, cyst nematodes).
Medical Significance: Some species are parasitic in humans and animals, causing diseases such as filariasis, ascariasis, and hookworm infections.
The study used to create the map above found:
There are 4.4 x 1020 nematodes present in the Earth’s topsoil, or in other words: for every human on the planet, there are 60 billion nematodes.
Summed, their weight equals to approximately four-fifths of the total human biomass.
We were surprised to find that by far most soil nematodes are present in cold regions such as the tundra and boreal forests in Alaska, Siberia and Scandinavia, and their numbers are much lower in tropical regions.
One explanation is that soil characteristics, such as soil organic carbon content, are key in regulating soil nematode abundances.
How do you feel about Nematodes? Please leave your comments below:
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