2. Nematodes are the most smallest
ecdysozoan animals.
The habitat in the sea, in fresh water and in
soil. Good topsoil may contain billions of
nematodes per acre.
Nematodes parasitize virtually every type of
animal and many plants.
3. Unique sensory amphids or phasmids
Body bilaterally symmetrical
Triploblastic body
Digestive system completed
Body wall has longitudinal muscles
Sensory system includes papillae and setae for
touch
Parthenogenesis occur rarely
(http://plpnemweb.ucdavis.edu/nemaplex/General/Physiolo
gy/repstrat.htm)
No respiratory or circulatory systems
4. Most nematodes are 5 cm long, and many
are microscopic but some parasitic
nematodes are over a meter in length.
The outer body is covering by non-cellular
cuticle which are secreted by the
hypodermis.
The most conspicuous feature of nematodes
is the present of pseudocoelom that act as a
hydrostatic skeleton.
5.
6.
7.
8. Layers of the cuticle is composed of collagen.
Function:
- The cuticle is a multi-functional
exoskeleton. It is a highly impervious
barrier between the animal and its
environment. It is essential for
maintenance of body morphology and
integrity.
- Plays a role in locomotion via attachments
to body-wall muscles
9. The longitudinal muscles arranged in 4
bands that projects inwards to the
pseudocoelom.
The body wall muscle in nematodes is that
the muscle extend to processes to synapse
with nerve cord rather than nerves
extending an axon to synapse with muscle.
The fluid filled pseudocoelom constitutes a
hydrostatic skeleton.
10. Parasitic nematodes are obligate aerobes.
The parasitic nematodes have an energy
metabolism; a Krebs cycle and cytochrome
system.
Nematodes derive energy through glycolysis
and some additional electron-transport
sequences.
11. The gut tube comprises a mouth, a muscular
pharynx, non-muscular intestine, a short rectum and a
terminal anus.
The cylindrical pharynx has The relaxation of muscles close
radial muscles that insert on the pharyngeal lumen and
the cuticular lining of its forces the food posteriorly
lumen and on a basement toward the intestine.
membrane.
When muscles in the anterior of the
pharynx contract, they open the lumen
and suck food inside.
12. Most nematodes are dioecious.
Males are smaller than females.
Fertilization is internal, and shelled zygotes or
embryos and stored in the uterus until
deposition.
There are four juvenile stages, each separated
by a shedding of the cuticle.
Many parasitic nematodes have free living
juvenile stages and others require an
intermediate host.
15. Large human roundworm (parasites of
human).
Ascaris Suum found in pig and have same
morphologically similar as in human.
Female of both species : up 30 length and can
produce 200000 egg a day.
Adult : occupy a small intestine
Egg : leave host body in feces.
16. Extreme resistance to adverse condition
Infection by: Ingestion of ova containing
embryos in contaminated food.
Effects;
alveoli : cause pneumonia
intestine : abdominal symptoms and allergic
reaction, in large number can block intestine.
17. Hookworms are so named because their
interior end curves dorsally, suggesting a hook.
Most common species is a Necator americanus
(L.necator,killer) whose female are up to 11 mm
and male 9mm in length.
They suck blood and pump it through their
intestine, partially digesting it and absorbing
the nutrients.
18. Infection by ; contact with the soil infested
with juveniles that burrow into the skin.
Effects ; cause anemia, mental retardation in
children, physical growth and general loss of
energy.
19. Trichinella spiralis tiny nematode that
responsible for the potential lethal disease
trichinosis.
Adult worm burrow in the mucosa of the host
small intestine, where females produce living
juveniles
Juveniles penetrate blood vessel and carried
throughout body then penetrate in skeletal
muscle cells.
20. Infection by; ingestion of infected muscles
Effects;
- juveniles cause astonishing redirection of
gene expression in host cell, which loses it
striation and become nurse cell.
- heavy infection may cause death.
21. Cause relatively little disease, but they are the
most common in the United States.
Length about 12 mm.
Migrate to anal at night to lay eggs, eggs
develop rapidly and become infective within 6
hours at room temperature.
22. Adult occupy large intestine and cecum.
Haplodiploidy ; male is haploid produced
parthenogenetically and female is diploid arise
from fertilized egg.
Infection by; Scratching the resultant itch
effectively contaminates hands and bedclothes.
23. Brugia malayi and etc
Infect the lymphatic system, and females may be
100 mm long.
Females worm release tiny microfilariae into the
blood and lymph of the host.
Microfilariae ingested by mosquitoes and develop
to the infective stages and can be transmitted by
mosquito to new host.
Long and repeated exposure can cause
elephantiasis.
Another filarial worm causes river blindness
carried by blackflies.
