Nematodes are one of the most abundant multicellular organisms on Earth. They are small, worm-like creatures that can be free-living or parasitic. Nematodes display a variety of life stages and can infect plants, insects, or other invertebrates. They have a tough outer cuticle and complete digestive system. Pathogenic nematodes can cause issues like intestinal obstruction or lung inflammation in hosts. Their life cycle involves eggs hatching into larvae that molt into adults, which mate and produce more eggs to continue the cycle. Nematodes have significant economic and ecological impacts as parasites and as parts of food webs.

1. University of Sulaimani
Subject: Biology
Name of the subject teacher: Fatmaya
Prepared by:
Group:
Semester: 4
Nematode
2022-2023

2. Outline
• Introduction
• General Characteristics Of Nematodes
• Pathogenicity and clinical features
• Diagnosis
• Role of nematodes in our life
• Life cycle of Nematodes

3. Introduction
• Nematodes are a group of lesser-known but the
most abundant group of multicellular organisms on
earth. They can be defined as a group of
thread/worm-like, transparent, bilaterally
symmetrical, pseudocoelomate and multicellular
organisms that are free-living or parasitic to plants
or animals. Numerically, they form the most
abundant phylum within the meio and mesofauna.
However, for many of us, nematodes are something
unseen and unheard.
• Nematodes are ubiquitous and associated with a
variety of organisms, including plants, insects, and
other invertebrates. They can have different life
stages, including parasitic (feeding on other
organisms), free-living, predatory, and insect
associates. Some nematodes are migratory, feeding
on different types of plants at different times.

4. General Characteristics Of Nematodes
• They are un-segmented.
• Elongated and cylindrical.
• They have separate sexes with separate
appearances.
• They have a tough protective covering or
cuticle.
• They have a complete digestive tract with
both oral and anal openings.
• The nematodes are free living (Majority) or
parasites of humans, plants or animals.
• They assume three basic morphologic forms:
Egg, Larvae and Adult worms.
Nematodes morphology

5. Pathogenicity and clinical features
• Adult worms in the intestine cause
abdominal pain and may cause
intestinal obstruction especially in
children.
• Larvae in the lungs may cause
inflammation of the lungs (Loeffler's
syndrome) - pneumonia-like symptoms.
• Diagnosis
• Examination of stool for eggs by direct
saline smear method.
• Demonstration of adult worms.
• Nematodes are microscopic creatures
that have a significant impact on the
economy and ecology of countries.
Annual crop losses due to nematodes
have been estimated at $80 billion,
and they play a significant role in the
food chain of subterranean
ecosystems. Nematodes are also
important parasites and predators in
the environment.
Role of nematodes in our life

6. Life cycle of Nematodes
• Nematodes have three main life-cycle stages: eggs,
larvae, and adults. Adult worms infect definitive
hosts (animals in which sexual development of the
worm occurs), whereas larval stages may also be
free-living or parasitize intermediate hosts or
invertebrate vectors. Eggs hatch into larvae, which
undergo several (often 4) metamorphoses to L2, L3,
and L4 (immature adults). The final moult releases
the immature adult, which then matures to an adult
worm. Male or female adults mate and the female
produces eggs, completing the cycle. L1 and L2
usually remain in the faeces, feeding on bacteria. L3
do not feed, surviving on energy reserves. They
move in water films on pasture. The L3 is the
infective stage which must be consumed by the host
animal for the life cycle to continue. Later moults
occur within the host.