Difference between revisions of "Category:Nematodes"

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== Nematode Superfamilies ==
 
== Nematode Superfamilies ==
 
<ncl style=compact maxdepth=5 headings=bullet headstart=2 showcats=1 showarts=1>Category:{{PAGENAME}}</ncl>
 
<ncl style=compact maxdepth=5 headings=bullet headstart=2 showcats=1 showarts=1>Category:{{PAGENAME}}</ncl>
 
<big>
 
 
[[:Category:Bursate Nematodes|'''BURSATE''']]
 
 
*[[Trichostrongyloidea]]
 
 
*[[Strongyloidea]]
 
 
*[[Ancylostomatoidea]] (Hook worms)
 
 
*[[Metastrongyloidae]]</big>
 
 
NOTE: the Trichostrongyloidea, Strongyloidea and hookworms are very closely related, and are often collectively known as '''"the strongyles"'''. Typically, they produce almost identical eggs, called '''"typical strongyle eggs"'''.
 
 
<big>[[:Category:Non-Bursate Nematodes|'''NON-BURSATE''']]
 
 
*[[Ascaridoidea]]
 
 
*[[Oxyuroidea]]
 
 
*[[Rhabditoidea]]
 
 
*[[Trichinelloidea]]
 
 
*[[Spiruroidea]]
 
 
*[[Filarioidea]]</big>
 
  
 
From the veterinary view-point, the nematodes are most conveniently grouped into '''superfamilies''' because their members often have similar life-cycles and epidemiological features. Superfamily names end in -oidea (the anglicised form is -oid, as in trichostrongyloid).
 
From the veterinary view-point, the nematodes are most conveniently grouped into '''superfamilies''' because their members often have similar life-cycles and epidemiological features. Superfamily names end in -oidea (the anglicised form is -oid, as in trichostrongyloid).

Revision as of 23:17, 26 April 2010



Introduction

Soybean Cyst Nematode and Egg, Scanning Electron Micrograph - Wikimedia Commons
Mononchidae eating a Mononchidae - Wikimedia Commons

Nematodes are one of the most prolific life-forms on this planet. Most are free-living, with species adapted to every imaginable habitat. Some are parasitic on plants, and others on animals. The animal parasitic nematodes form a large and diverse array of organisms.

The Nematodes

Recognition Features

  • A unique feature of the nematodes is that the fluid in the body cavity is maintained under high pressure (this is why nematodes often burst after collection)
  • They therefore have a tough elastic cuticle which often forms elaborate structures useful for identification
  • A muscular pharynx is needed to pump food into the intestine
  • The shape of the pharynx is characteristic in some groups
  • There is a nerve ring around the pharynx and four longitudinal nerves with ganglia that co-ordinate movement (many anthelmintics act by disrupting neuromuscular co-ordination)
  • The sexes are separate:
    • the female tail generally ends in a blunt point
    • males usually have two chitinous rods that can be protruded through the cloaca to hold the female - these are called spicules and, being chitinous, are easily seen under the microscope. As these differ in shape and size between species, they are very useful in identification
  • The bursate nematodes are characterised by a large expansion of the cuticle of the male tail to form a clasping organ (the bursa)
  • Other modifications of the cuticle on both male and female nematodes useful for identification include:
    • alae (wing-like protrusions)
    • vesicles (swellings around the whole circumference of the body)
  • The heads of some nematodes have structures such as:
    • leaf-like lips around the mouth (the leaf-crown)
    • a buccal cavity
    • teeth or cutting plates

Feeding Habits

  • Many intestinal nematodes are closely applied to the mucosal surface
  • Some swallow ingesta and/or host secretions.
  • Others suck a plug of mucosa into the buccal cavity (plug feeders), leaving a circular ulcer
  • Yet others bury their heads deep into the mucosa and suck blood

General Life-Cycle

  • The basic life-cycle is very simple:
    • egg → L1 → L2 → L3 → L4 → adult
  • With a moult in between each larval stage
  • But there are many variations on this theme

Nematode Eggs

  • These vary greatly in appearance and are very useful for diagnosis as they can often be detected and counted in faecal samples
  • NOTE: we use the typical strongyle egg to provide us with a yard-stick for comparing sizes. A "large egg", for example, means larger than a strongyle egg. A typical strongyle egg is approximately 80µm long

Nematode Superfamilies

<ncl style=compact maxdepth=5 headings=bullet headstart=2 showcats=1 showarts=1>Category:Nematodes</ncl>

From the veterinary view-point, the nematodes are most conveniently grouped into superfamilies because their members often have similar life-cycles and epidemiological features. Superfamily names end in -oidea (the anglicised form is -oid, as in trichostrongyloid).

Nematodes of Different Species

Cattle Nematodes

Sheep Nematodes

Goat Nematodes

Horse Nematodes

Pig Nematodes

Poultry

Small Animals

Donkey



Occlusion of pancreatic ducts sometimes happens Pancreas Parasitic - Pathology

Subcategories

This category has the following 2 subcategories, out of 2 total.

B

N

Pages in category "Nematodes"

The following 4 pages are in this category, out of 4 total.