Nematotes

Nematodes and Namatology

the name nematode was derived from Greek words nema means thread iodes means resembling.

Father of nematology is  N.A. Cobb (1915), American nematology.

 Nematology is an important branch of biological science which deal with a complex diverse group of roundworms known as nematodes.

It is also known as roundworms .

Nematodes are circular in cross section.

They are free living ,aquatic and terrestrial or parasitic in plant and animals.

They are bilaterally symmetrical, triploblastic and pseudocoelomate animals.

Sex organ are separate is called Dioecious that is male and female are distinct.

Female nematodes are longer than males.

Nematodes are unsegmented , Vermiform and colour less animals.

plant parasitic nematodes are slender, elongate, spindle shaped ,or fusiform, tapering towards both ends    and circular in cross section.

The length of nematode may vary from 0.2 mm.

Their body width vary from 0.01 to 0.05 mm.

Fertilization is internal and development may be direct .

Nematodes that occur worldwide in essentially all environment.

Swelling increased the reproductive potential of the organism.

The free living saprophytic nematodes are generally larger in size.

The animals and human parasitic helminthes may have length of few centimetre to even a metre or more.

Helminth parasitic whale fish is about 27 feet long.

Characteristics of Nematodes.

• Vermiform, round in cross – section, covered with a three – layered cuticle.

• Growth accompanied by molting of juvenile stages, usually four juvenile stages.
• Oral opening surrounded by 6 lips and 16 sensory structures.
• Possess unique cephalic sense organs called amphids.
•  Body wall contains only longitudinal muscles connected to longitudinal nerve chords by processes extending from each muscle. 
• Unique excretory system containing gland cells or a set of collecting tubes.
• Longitudinal nerve cords housed within the thickening of the hypodermis.

the study on these animals and human parasites are known as helminthology.

Nematodes are also known as eelworms in Europe.

Nematodes that are parasite of man and animals are called helminthes and the study is known as helminthology.

Plant parasitic forms are called nematodes and study is known as plant nematology.

Outer body tube

The outer body tube or  body  includes the cuticle, hypothermia and somatic muscles. 

 the body wall protects the nematode from the harsh environment serve as the exoskeleton and provide the mechanism for movement of the organism through the soil and plant tissue.

 the body wall contain much of the nervous system and secretary - excretory system and play a role in the gaseous exchange.

The damage to plants caused by nematodes is often overlooked because the associated symptoms including slow growth, stunting,and yellowing can also be attributed to nutritional and water related disorders.

 the United state the nematode are known to cause 6% loss in field crops ,12% loss in fruits and nuts 11% loss in vegetables and 10% loss in ornamental.

In India  , the cereal cyst nematode, Heterodera avenae cause the molya disease of wheat barley in Rajasthan, Punjab ,Haryana Himachala Pradesh and Jammu Kashmir.

The loss due to this nematode is about 32 million rupees in wheat and 25 million rupees of Barley in Rajasthan state alone.

Example of nematodes:- Ascaris (Roun worm), Wuchereria (Filaria worm), Ancylostoma (Hookworm).

Mineral and nutrition.

Transport in plants