Phylum – Aschelminthes
The body of the aschelminthes is circular in cross-section, hence, the name roundworms.
They may be freeliving, aquatic and terrestrial or parasitic in plants and animals.
Roundworms have organ-system level of body organisation.
They are bilaterally symmetrical, triploblastic and pseudocoelomate animals.
Digestive System: Alimentary canal is complete with a well developed muscular pharynx.
An excretory tube removes body wastes from the body cavity through the excretory pore.
Sexes are separate (dioecious), i.e., males and females are distinct.
Reproduction: Often females are longer than males.
Fertilisation is internal and development may be direct (the young ones resemble the adult) or indirect.
Body wall with thick resistant, cuticle, cellular orsyncytial epidermis, and onty longitudinal muscle fibres in
four bands. Cuticle is made up of sceleroprotein, which is resistant to digestive enzyme of fibres in
fourbands. Cuticle is made up of sceleroprotein, which is resistant to digestive enzyme of host.
Excretory system orglandular organs (Renette gland cells) orcanals orboth. Excretory canal formed by a
huge excretory renette call at the juvenile stage.
Nervous system with circumenteric ring and anterior and posterior nerves.
Sense organs poorly developed, Amphids act as olfactory receptor or gustatoreceptor.
Labial Papillae- Specially for gustation.
Phasmids : Placedat lateral sides of body in the tail region and are glandulo sensory structures. Act as a
chemoreceptor .:. Dioecious with sexual dimorphism. Male smaller than female. Gonads simple and coiled.
Male
genitalducts lead into cloaca. Female genital ducts urith a sepearate opening. No asexual reproduction.
Eutely number of cells and nuclei of cells do not change after maturity, they remain constant.
Fertilization internal. Development usaly direct, (the young one resemble the adult) with or without an
intermediate host.
Examples:
• Ascaris (Round Worm),
• Wuchereria (Filaria worm),
• Ancylostoma (Hookworm).
Classification
Chitwood (1993) divided nematodes into two classes: on the basis of presence or absence of Phasmids.
• Examples: Ascaris (Round Worm), Wuchereria (Filaria worm), Ancylostoma (Hookworm)
The body of the aschelminthes is circular in cross-section, hence, the name roundworms.
They may be freeliving, aquatic and terrestrial or parasitic in plants and animals.
Roundworms have organ-system level of body organisation.
They are bilaterally symmetrical, triploblastic and pseudocoelomate animals.
Digestive System: Alimentary canal is complete with a well developed muscular pharynx.
An excretory tube removes body wastes from the body cavity through the excretory pore.
Sexes are separate (dioecious), i.e., males and females are distinct.
Reproduction: Often females are longer than males.
Fertilisation is internal and development may be direct (the young ones resemble the adult) or indirect.
Body wall with thick resistant, cuticle, cellular orsyncytial epidermis, and onty longitudinal muscle fibres in
four bands. Cuticle is made up of sceleroprotein, which is resistant to digestive enzyme of fibres in
fourbands. Cuticle is made up of sceleroprotein, which is resistant to digestive enzyme of host.
Excretory system orglandular organs (Renette gland cells) orcanals orboth. Excretory canal formed by a
huge excretory renette call at the juvenile stage.
Nervous system with circumenteric ring and anterior and posterior nerves.
Sense organs poorly developed, Amphids act as olfactory receptor or gustatoreceptor.
Labial Papillae- Specially for gustation.
Phasmids : Placedat lateral sides of body in the tail region and are glandulo sensory structures. Act as a
chemoreceptor .:. Dioecious with sexual dimorphism. Male smaller than female. Gonads simple and coiled.
Male
genitalducts lead into cloaca. Female genital ducts urith a sepearate opening. No asexual reproduction.
Eutely number of cells and nuclei of cells do not change after maturity, they remain constant.
Fertilization internal. Development usaly direct, (the young one resemble the adult) with or without an
intermediate host.
Examples:
• Ascaris (Round Worm),
• Wuchereria (Filaria worm),
• Ancylostoma (Hookworm).
Classification
Chitwood (1993) divided nematodes into two classes: on the basis of presence or absence of Phasmids.
• Examples: Ascaris (Round Worm), Wuchereria (Filaria worm), Ancylostoma (Hookworm)
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