Nematodes

Pronunciation

How to pronounce Nematodes: /nɛməˈtoʊdiːz/

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Summary

Nematodes are a diverse phylum known for both free-living and parasitic species, inhabiting a wide array of ecosystems and playing significant roles in ecological processes.

Physical Characteristics

Typically 3-11 mm in length; can range from microscopic (5 μm thick, 0.1 mm long) to over 1 m in length for some parasitic species. Body may be slender or ornamented with ridges, rings, bristles, or distinctive structures. The head is radially symmetrical with sensory bristles and mouth often featuring three or six lips with teeth.

Identification Tips

Nematodes can be difficult to distinguish; generally, they have a cylindrical shape with a tapered end and a unique cuticle structure.

Habitat

Largely found in forested areas, as well as in a broad range of environments from marine to freshwater, soils, and extreme conditions from polar regions to tropics and altitudes.

Distribution

Worldwide; most diverse in the Neotropics. In our area, eastern: 2 widely distributed species, two with scattered records, and one endemic to Florida.

Diet

Most species are free-living, feeding on microorganisms such as bacteria, algae, fungi, and detritus; many species are also parasitic, feeding on the tissues of hosts.

Life Cycle

Life cycles differ widely; free-living nematodes hatch into larvae that resemble adults, while parasitic nematodes may have complex life cycles involving multiple host species.

Reproduction

Most nematode species are dioecious; some hermaphrodites exist. Reproduction is primarily sexual, with males and females copulating; some engage in self-fertilization.

Predators

Nematodes are preyed on by various organisms including nematophagous fungi and some invertebrates.

Ecosystem Role

Nematodes play a crucial role in nutrient cycling, soil health, and regulation of microbial communities. They can also influence plant health as both beneficial and harmful organisms depending on the species.

Economic Impact

Certain nematodes can cause severe crop losses; beneficial nematodes are used in biological pest control, while pest species can be vectors of plant viruses.

Health Concerns

Some nematodes are pathogenic to humans and other animals causing diseases like ascariasis, filariasis, and trichinosis.

Collecting Methods

• Soil sampling
• Berlese funnel extraction
• Direct observation

Preservation Methods

• Ethanol
• Formalin
• Freezing

Evolution

Nematodes belong to the clade Ecdysozoa, showing evolutionary adaptation to diverse ecosystems.

Misconceptions

Nematodes are often confused with flatworms; unlike flatworms, nematodes have a tubular digestive system with openings at both ends.

Tags

• Nematoda
• Roundworms
• Ecology
• Parasitology
• Biological control