Protozoa and Nematodes

Protozoa
Protozoa can be considered unicellular animals (formed by a single cell) that have dimensions ranging between 2 and several hundred µm (remember that 1000 µm = 1 mm ). They are extremely abundant and well distributed in the entire thickness of the first centimetres of soil and their geographical distribution covers climates that extend from the warm and dry areas typical of deserts to cold and damp ones typical of the tundra. Flagellates and amoeboidsrepresent the majority of soil protozoa, specially with respect to those very particular biological communities that form close to the roots of plants (rhizosphere). Protozoa are particularly important in the global ecology of the soil and their role is basically that of keeping a check on the bacteria population that they feed on.
Nematodes
Nematodes – that are, as can be remembered, small cylindrical worm-shaped pseudocelomates, i.e. without a real coelom – have dimensions that vary from a few tens of  ?m to about 2 mm. They carry out a fundamental function in soil ecology because, depending on the species, they have different life styles: in fact, they can be predators or parasites of plants and animals. However, briefly it can be stated that, in the soil, the role of the nematodes is mainly that of keeping the abundance of other organisms in check and to demolish organic substances. Moreover, nematodes, as has been stated also for protozoa, are very efficient predators of bacteria.

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