2ClassNotes.com - Home
Banner Here

Search

ePapers

Central Board of Secondary Education

Science

12

Zoology

   

Search for

Keyword

Phylum Nemathelminthes - some common examples

Many species of Rhabditis are free living and semi-parasitic forms

Zoology [Science]

Central Board of Secondary Education [12]

12/29/2009Print This PageTell - A - FriendAdd to Wish ListReport Error

Some common examples of Phylum Nemathelminthes

  1. Rhabditis
    Many species of Rhabditis are free living and semi-parasitic forms. Rhabditis maupasi lives in soil. The males are smaller than females. The male has a single tubular testis, however the female has two ovaries. Life cycle is simple and direct.
     
  2. Enterobius (Oxyuris)
    Enterobius vermicularis is commonly known as pin worm. It is most common parasitic nematode of man throughout the world.

    Its incidence however is greater in women and children. Adult worms live in the caecum, appendix and colon. Sexes are separate. Males are short and they have curved end with a single spicule. Females are long and they have straight pointed end. The male is monorchic and female didelphic, Egg contains rhabditiform larva.

    The anal itching takes place in Enterobius infection because female worm lay eggs in peri-anal region. Pinworm causes entrobiasis or oxyuriasis involving loss of appetite, insomnia, restlessness, abdominal pain and appendicitis.
     
  3. Ancylostoma (Hook worm)
    They are the most dangerous parasitic round worms of man. They differ from Ascaris in the absence of lips but they have three chitinous plates that bear sharp cutting teeth.



    Hook worms flourish under primitive conditions where people go bare foot, modern sanitary conditions do not exit and human faeces are disposited in the ground. Larva enters the human body from moist soil by boring through the skin of the feet. The adult worms live parasitically in the intestine of man where they suck blood, lymph, bits of mucous membrane and tissue fluids from the lining of the intestinal wall. It causes acute anaemia due to extensive injury to the host intestinal wall. It also retards growth of the body in the children. It causes mental and physical deficiency. The disease is called ancylostomiasis.
     
  4. Wuchereria (Filarial worm)
    Wuchereria bancrofti lives as an endoparasite in the lymphatic vessels and lymph nodes of human beings. It is a digenetic parasite. Human being is a primary host whereas Culex or Aedes mosquito is the intermediate host. Wuchereria feed on the blood and lymph. The female gives rise to juvenile called microfilariae. When mosquito bites the infected person these juveniles reach the mid gut of the mosquito along with blood. After penetrating the stomach wall they reach the haemocoel and finally migrate to the proboscis of the mosquito. When the infected mosquito penetrates its proboscis into the skin of the human being, the juveniles leave the proboscis, and then reach the lymph glands through the lymphatic and blood vascular system.

    Sexes are separate. The female is larger than the male. The tail of the male is coiled like tendril and has a pair of unequal copulatory spicules. Female has an anus while male bears cloacal aperture.

    In the lymph glands, the juveniles develop into adults. It blocks the lymphatic system resulting in inflammation of lymph glands and other pathological conditions. It causes a disease known as elephantiasis in the legs and arms.
     
  5. Dracunculus medinesis
    It is commonly known as guinea worm. It occurs in subcutaneous tissue of man. The toxic secretions of the parasite causes a blister on the skin of the host. It is digenetic parasite. The primary host in human being and Cyclops (water flea) is the intermediate host. Sexes are separate. Female is very long while male is short. The parasite causes itching, diarrhoea, nausea, vomiting and eosinophilia. The guinea worm has been completely eradicated from India.
     
  6. Trichuris (Whip worm)
    The parasite resides in the caecum, appendix and colon of man, especially children, in warm moist climates. The infection spreads through contaminated food and water containing embryonated eggs. Its infection causes abdominal point, diarrhoea and anaemia.


     
  7. Trichinella spiralis (Trichina worm)
    It occurs in the voluntary muscles of man and other mammals in the form of a coiled encysted larva. It causes a disease known as "trichinosis".
     
  8. Loa loa (Eye worm)
    It is a filarial round worm of central and western Africa. The adult migrates through the subdermal connective tissues of human host. Sometimes they pass across the eye ball. Local swelling accompany these migrations. Tabanus flies act as transmitting vector.
     

12/29/2009Print This PageTell - A - FriendAdd to Wish ListReport Error

Related Words:

Phylum Nemathelminthes, Rhabditis, Enterobius, Oxyuris, Pin Worm, Rhabditiform Larva, Monorchic, Didelphic, Ancylostoma, Hook Worm, Ancylostomiasis, Wuchereria, Filarial Worm, Microfilariae, Culex, Aedes Mosquito, Dracunculus Medinesis, Guinea Worm, Trichuris, Whip Worm, Embryonated Eggs, Trichinella Spiralis, Trichina Worm, Trichinosis, Eye Worm, Tabanus Flies

LOGIN

Username

Password

New UserForgot Password