Nematodes are triploblastic, bilaterally, symmetrical, unsegmented, pseudocoelomate, vermiform and colourless animals. The plant parasitic nematodes are slenderelongate, spindle shaped, or fusifororm tapering towards both ends nd circular in cross section.
The following are the characteristicsof member of phylum Nemata.
- Inhabit marine, freshwater and terrestrial environmentals as free- livers and parasites.
- Bilaterally, symmetrical, triploblastic, unsegmentedand pseudocoelomates.
- Vermiform, round in cross- section, covered with a three- layered cuticle.
- Oral opening surround by 6 lips and 16 sensory structures.
- Unique excretory system containing gland cells or a set of collecting tubes.
They are generally cylindical in shape, tapering towards the head and tail. Female of a few species lose their worm shape as they mature, becoming greatly enlarged in diameter and assuming varying forms, such as pear, lemon, or kidney shapes. In few genera, the females on maturity assume pear shape (Meloidogyne), globular shape (Globodera), reniform (Rotylenchelus reniformis) or saccate (Tylenchulus semipenetrans). Sexual dimorphism occurs in some members of Tylenchida, where females becomes swollen and males are vermiform.
The lenght of the nematode may vary from 0.2 mm (Paratylenchus) to about 12.0 mm (Paralongidorus epimikis). Their body width varies from 0.01 to 0.05 mm. Nematodes that attack plant are worms, mostly microscopic in size ranging from 0.25 mm to 3.0 mm(1/100-1/8 inch) long.
BODY REGIONS
The body consists of an external cylinder (the body wall) and an internal cylinder (the digestive system) separated by a pseudocoelomic cavity filled with fluid under pressure and containing a number of cells and other organs such as the reproductive tracts. About 99% of all known nematodes have a long, thin cylindrical body shape, whichis round in cross-section and tapered towards both ends, although usally more towards the posterior or tail end. The tail may be short or long and varies in form from broadly rounded to filiform. The tail may also differ in shape between developmental stages or between sexes.
The nematode can be divided in to a dorsal, a ventral and two lateral sectors. The secretory- excretory (S-E) pore, vulva and anus in the female or the cloacal opening in the male are all located ventrally whereas the lateral regions may be identified by the apertures of the amphids (few exceptions), deirids and phasmids, when present. The mouth opening is usally located terminally at the anterior end. They do not possess a specialized circulatory or respiratory system. The exchange of gases is thought to occur through the cuticle and circulation proceeds through the movement of fluids within the pseudocoelom and by simple diffusion across membranes.
The nematode body is divided in to three regions.They are
The lenght of the nematode may vary from 0.2 mm (Paratylenchus) to about 12.0 mm (Paralongidorus epimikis). Their body width varies from 0.01 to 0.05 mm. Nematodes that attack plant are worms, mostly microscopic in size ranging from 0.25 mm to 3.0 mm(1/100-1/8 inch) long.
The body consists of an external cylinder (the body wall) and an internal cylinder (the digestive system) separated by a pseudocoelomic cavity filled with fluid under pressure and containing a number of cells and other organs such as the reproductive tracts. About 99% of all known nematodes have a long, thin cylindrical body shape, whichis round in cross-section and tapered towards both ends, although usally more towards the posterior or tail end. The tail may be short or long and varies in form from broadly rounded to filiform. The tail may also differ in shape between developmental stages or between sexes.
The nematode can be divided in to a dorsal, a ventral and two lateral sectors. The secretory- excretory (S-E) pore, vulva and anus in the female or the cloacal opening in the male are all located ventrally whereas the lateral regions may be identified by the apertures of the amphids (few exceptions), deirids and phasmids, when present. The mouth opening is usally located terminally at the anterior end. They do not possess a specialized circulatory or respiratory system. The exchange of gases is thought to occur through the cuticle and circulation proceeds through the movement of fluids within the pseudocoelom and by simple diffusion across membranes.
The nematode body is divided in to three regions.They are
- Outer body tube or body wall
- Inner body tube or alimentary canal and
- body cavity or pseudocoelom in which excretory, nervous and reproductive system are present
1. Outer body tube
Consists of three layer; the cuticle, epidermis (hypodermis) and somatic muscle layer.
Cuticle: is the outermostlayer non cellular secreted by epidermal cells derived from ectoderm serves as exoskeleton and protect the inner soft body tissues.
Cuticle has three layers
- Outer cortical- has keratin and collagen disulphide group- give resistance nature
- Matrix- consists of protein resembling collagen. It is not metabolically active layer.
- Fibre layer- protect nematode from adverse environment.
It lies between cuticle andsomatic layer.It is responsible for formation of cuticle. In higher nematodes it is rich in lipids and glycogen which serve as source of reserve energy.
Hypodermal glands
Various
for ARS and NET preparation
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