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Nematode Structure and Function (view source)
Revision as of 10:04, 21 May 2010
, 10:04, 21 May 2010Created page with '=== 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 co…'
=== 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[[Category:Nematodes]]
*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[[Category:Nematodes]]