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Did you know that nematodes are the fourth largest group (or phylum) within the Animal kingdom? It includes numerous species that maintain a close relationship, most of the time harmful, with humans, as well as with wild and domestic animals, wild and ornamental plants. For this reason, nematodes are considered one of the most important, numerous and diverse groups of invertebrate animals.
If you want to know more about these surprising organisms of aquatic, terrestrial and parasite habits, continue reading this Green Ecologist article in which you will learn what are nematodes: characteristics, classification and examples.
What are nematodes
Commonly known as roundworms, nematodes are one of the great taxonomic phyla in which they are classified invertebrates of the Animal kingdom or Animalia.
Generally, nematodes are known for their ability to infect and cause diseases, both in plants and animals, being responsible for the loss of crops and ornamental plants, as well as gastrointestinal infectious diseases in humans and other animals (mammals and fish, mainly ). In this way, nematodes are considered one of the phytopathogens and parasites most widespread in any corner of the planet.
Nematode characteristics
Between the main characteristics of nematodes stand out:
- They live both freely in arid and humid soils, in fresh and salt water habitats, as well as parasitizing plants and animals on which they feed.
- Its size is very varied, from a few millimeters to more than half a meter.
- Its body is round and elongated, cylindrical in shape and without segments. Its symmetry is bilateral.
- The mouth of nematodes has different structures that allow them to attach to tissues and obtain food, such as teeth, plates and even mouth hooks.
- The outer surface of adult nematodes is very resistant, they have a cuticle and several muscular layers.
- Regarding their diet, nematodes have developed different strategies, such as: aspiration for ingestion of blood, absorption of destroyed tissues, as well as intestinal content and nutrients present in different body fluids (in animals) or sap ( in plants).
- Nematode reproduction can be both sexual and asexual, through parthenogenesis, fragmentation or embryogenesis. Depending on the environmental and survival conditions in which the adults find themselves, they will choose one reproductive method over another.
Classification of nematodes
The phylum of nematodes include some 25,000 species. These invertebrate animals have evolved throughout their biological history in order to adapt to new hosts to parasitize, both within the animal and plant kingdoms. For the nematode classification, the most widely used classical method is based on morphological criteria, which allow distinguishing within the nematode phylum, the following classes and subclasses:
Class Adenophorea
- Enoplios (subclass Enoplia)
- Chromadoria (subclass Chromadoria)
Secernentea Class
- Rhabditids (subclass Rhabditia)
- Senephrenics (Spiruria subclass)
- Diplogasteries (subclass Diplogasteride)
In the next section, we will learn more about the world of nematodes with concrete examples of common species.
Examples of nematodes
Here is a list of examples of nematode species, both species and genera that are commonly known in many cases for the disease or symptoms that cause:
Examples of Parasitic Nematodes in Animals
- Roundworm (Ascaris lumbricoides)
- Hookworm nematode (genus Ancylostoma)
- Whipworm or whipworm (Trichuris trichiura)
- Anchylostomiasis nematode (Ancylostoma duodenale)
- American necator (Necator americanus)
- Strongioloidiasis nematode (Strongyloides stercoralis)
- Guinea worm (Dracunculus medinensis)
- Anisakiasis nematode (genus Anisaki)
- Pinworms (Enterobius vermicularis)
- Trichinae (Trichinella spiralis)
- Filariasis nematode (order Spirurida)
Examples of plant parasitic nematodes
- Potato root nematode (genus Globodera)
- Migrating ectoparasitic nematode (genus Xiphinema)
- Gall-inducing nematodes (genus Meloidogyne)
- Cystic nematodes (Heterodera fici)
- Spiral nematode (genus Helicotylenchus)
- Root knot nematode (genus Meloidogyne)
- Root lesion nematode (genus Pratylenchus)
- Burrowing nematode (Radopholus similis)
- Leaf nematode (genus Aphelenchoides)
- Rot nematode (Ditylenchus destructor)
- Stem and bulb nematode (Ditylenchus dipsaci)
Below you can see images of some of these examples of nematodes.
If you want to read more articles similar to What are nematodes: characteristics, classification and examples, we recommend that you enter our Biodiversity category.
Bibliography- Ortuño, N. & Oros, R. (2002) Nematodes that attack ornamental crops. Journal of Integrated Pest Management and Agroecology (Costa Rica). Volume 66, pp: 76-81.
- Sarmiento, L., Tantaleán, M. & Huiza, A. (1988) Parasitic nematodes of man and animals in Peru. Biological Sciences Faculty. National University of La Libertad, Trujillo. Peru.
- López, L. & Jansson, H. (2000) Soil biodiversity: biological control of phytopathogenic nematodes by nematophagous fungi. Journal of Biodiversity Notebooks.
