3. Classification of NEMATODES
• SYSTEMIC CLASSIFICATION
KINGDOM :ANIMALIA
PHYLUM:NEMATHELMINTHES
CLASS : NEMATODA
SUB CLASS : ADENOPHOREA
SECERNENTEA
4. Nematodes
• General characteristics –
• Size – 1mm to 1 m
• Shape - Elongated, Cylindrical, Unsegmented
• Head end – Hooks and sucker absent, Well developed buccal capsule with
teeth or cutting plates seen in some species.
• Alimentary canal – Complete with anus.
• Body cavity – Present and known as psuedocoele. viscera remains
suspended in the pseudocoele.
• Sex – Separate (Dioecious)
5. Life Cycle
• Consists of 4 larval stages and 1 adult form
• Requires one host (except filarial worms, Dracunculus – need
two hosts).
• Optimum host – Man
• Nematodes localise in intestinal tract and eggs pass out with
the faeces of the host.
6. Modes of infection
• By Ingestion of eggs
• Eggs : Ascaris, Enterobius
• Larvae within intermediate host : Dracunculus.
• Encysted larvae in muscle : Trichinella
• By penetration of skin: Ancylostoma, Strongyloides
• By blood sucking insects : Filariae
• By inhalation of dust containing eggs : Ascaris, Enterobius
7. Classification
• On the basis of habitat of adult worms
• Intestinal Human Nematodes
» Small intestine : Ascaris lumbricoides, Ancylostoma duodenale,
Strongyloides stercoralis, Trichenella spiralis
» Large intestine : Trichuris trichiura, Enterobius vermicularis
• Somatic Human Nematodes
» Lymphatics : Wuchereria bancrofti, Brugia malayi, Brugia timori
» Skin/subcutaneous : Loa loa, Dracunculus medinensis
» Mesentry : Mansonella ozzardi, Mansonella perstans
» Conjuctiva : Loa loa
• Zoological Classification
Editor's Notes
Free living
Nematode means thread like
Strongyloides – milli metre size
Dracunculus – metre size
Male is generally shorter than female and its posterior end is curved or coiled ventrally.
Two hosts are man (optimum) and inesct vector or cyclops
