Phylum nematoda (nemathelminthes ), Biology

PHYLUM  NEMATODA (= NEMATHELMINTHES )

Definition and Introduction                                                                            

Bilateral  and protostomial  organ grade  eumetazoans  in which the space  between  body  wall and  alimentary canal is a false body  cavity ,or pseudocoel , derived , from embryonic  blastocoels. The term  Nematoda  literally  means  threadworms  or roundworms (Gr. Nema = thread + eidos = form )About 12,000 species  known.

Brief History

 Ancient people were  familiar with  certain large  sized  nematode  parasite  of domestic animals . Minute nematodes were discovered only  after  the invention  of microscope.  Linnaeus (1758) included these  in vermes  Rudophi (1793,1819)  included  these under Nematoidea Gegenbaur  (1859 )  ultimately  proposed  Nema  thelminthes for  these.

Important Characters

1.       Many  endoparasited  of various animals  and plants other  free living  and widely distributed  in all  sorts of water  and damp soil.

2.       Mostly  minute or small , some  large ( 1mm to 25 cm)  some  upto  several  metres long.

3.       Slender ,  cylindrical , elongated body  usually  tapering  towards  both  ends, unsegmented .

4.       Body  wall formed  of a thick , tough  and shiny cuticle,  a syncytial   hypodermis  beneath cuticle. And  innermost  layer  of peculiar ,large  and longitudinally extended  and muscle cells  arranged in four  quadrants .

5.       The  false body cavity  or pseudocoel  is spacious  with  a fluid  but  no free cells

6.       Straight  alimentary tract with  terminal mouth and  anus.

7.        Circulatory  system and respiratory organs absent. A simple  excretory system , comp aratively simpler or complicated  sensory  organs and well developed nervous  system, present .

Reproductive  system  well developed. Usually  unisexual with  sexual  dimorphism,Many  kinds  of nematodes  are arasites of useful plant and domestic animals .  Some of these  are pathogenic to their hosts, causing serious diseased. Even man is a host for more than 50  species . of  which  ascaris  lumbricoides . and  Enterobius  vermicularis  are  very  common ,Other  human  nematodes are wuchereria which  causes   filarial , Trichinella  causing  trichinosis ,and  ancylostoma causing  hookworm disease.   

Posted Date: 10/4/2012 2:57:45 AM | Location : United States







Related Discussions:- Phylum nematoda (nemathelminthes ), Assignment Help, Ask Question on Phylum nematoda (nemathelminthes ), Get Answer, Expert's Help, Phylum nematoda (nemathelminthes ) Discussions

Write discussion on Phylum nematoda (nemathelminthes )
Your posts are moderated
Related Questions
What is Placoid scale? Elaborate in detail. Scales characteristic of cartilaginous fish. Formed from the dermis, scale is anchored in that layer by a basal plate composed of de

Is it possible for a hermaphrodite species to present cross-fecundation? There are hermaphrodite species of animals and plants that present cross-fecundation mainly because of

Surveys - Accidents in Industries The surveys done in industries have pointed out that leading cause of accidents is the overexertion or workers working beyond their physical

Making leaf collections Collect young leaves of as many varieties of plants as possible. Place various layers of news- paper or blotting paper on a firm, smooth board. Next org

Define Isotope Dilution Method? The measurement of total body water (TBW) is based on the principle of hydrometry. You must be aware that water is the most abundant substance i

Cost due to Injury to Worker Medical cost - medicine, surgery, hospitalization, extended treatment. Working time lost due to injury or death. Time loss of cowork

Critical thinking the organization of a rock is much simpler than that of living things. By what other criteria can a rock be well-known from living things? Rocks are not comp

Q. Enlist the various modalities available for sterility assurance? Various modalities available for sterility assurance are a) Prevention of overloading b) Chemical indi

Animal tissue

Describe in brief about retina The retina is a highly complex layer of nervous tissue. The photoreceptors are rods and cones for scotopic and photopic vision respectively. The