A nematode is an unsegmented pseudocoelomate worm
(such as Caenorhabditis elegans
) belonging to the phylum Nematoda
which is generally round, one to two millimeter
s in length, and pointed at both ends. There are both parasitic
and free-living species
. The parasites can be found in all types of animals (both vertebrate
s and invertebrate
s) and in plant
s. The free-living species can be found in shallow water
environments (both sea
water and freshwater
) and in soils.
Over 12,000 species of nematodes have been named and described by scientists; a single scoop of garden soil contains about a million microscopic nematodes.
Over 50 species of parasitic nematodes can infect humans. They are a major cause of disease and death worldwide, particularly in tropical areas. Some of the most common human parasites include:
Reference: Part of the information here was found in the book Biology by Helena Curtis (Worth Publishers, Inc.) The rest was taken from personal notes.