|
|
| (4 intermediate revisions by one other user not shown) |
| Line 1: |
Line 1: |
| − | {unfinished}
| + | #REDIRECT[[:Category:Nematodes]] |
| − | | |
| − | == Introduction ==
| |
| − | [[Image:Soybean cyst nematode EM.jpg|thumb|right|150px|Soybean Cyst Nematode and Egg, Scanning Electron Micrograph - Wikimedia Commons]] | |
| − | [[Image:Mononchidae eating a Mononchidae.jpg|thumb|right|150px|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 ==
| |
| − | | |
| − | <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).
| |
| − | | |
| − | == Nematodes of Different Species ==
| |
| − | [[Cattle]] [[:Category:Cattle Nematodes]]
| |
| − | | |
| − | [[Small Ruminants]]
| |
| − | | |
| − | [[Horses]]
| |
| − | | |
| − | [[Pigs]]
| |
| − | | |
| − | [[Poultry]]
| |
| − | | |
| − | [[Small Animals]]
| |
| − | | |
| − | [[Endoparasites - Donkey|Donkey]]
| |
| − | | |
| − | | |
| − | | |
| − | | |
| − | | |
| − | Occlusion of pancreatic ducts sometimes happens [[Pancreas Parasitic - Pathology]]
| |
| − | [[Category:Nematodes]]
| |