Nematodes

• Nematodes


  also known as Roundworms
• Nematodes


  most abundant animals on Earth
• 75% of all nematodes species are free-living in marine, freshwater and soil habitats
• 500,000 species ( 10,000 described)
• 2,000 species are parasites of plants
• General Characteristics of Nematodes

  • unsegmented
  • 2mm length
  • sexes are separated (dioecious)
  • males are smaller than females
  • posterios portion of male is curved and coiled
• Gen. characteristic of nematodes

  it possess a pseodocoel. It is body cavity filled w/ fluid
• Gen. characteristic of nematodes

  the lumen of pharynx is characteristically triradiate
• Body wall consists of...

  • cuticle
  • hypodermis
  • body wall musculature
• Composition of Cuticle

  • cortical
  • median
  • basal zone
• Cortical

  • outer most zone
  • contains highly resistant protein called cuticulin
• Median


  • contains fine striations
• Basal zone


  • composed of 2 or 3 fibrous layers
• Most prominent feature in the Nervous system of nematodes is the Nerve ring or circumesophageal commissure
• sensilla

  small sense organs
• mouth


  circular opening surrounded by a maximum of six lips
• buccal cavity


  tubular or funnel-shaped for sucking purposes
• esophagus


  important for specie identification
• 2 basic types of excretory system

  • glandular type
  • tubular type
• excretory pore


  presence of median ventral duct and a pore is called?
• Male reproductive organ


  • situated in the posterior 3rd
  • single coiled or convoluted tube
• female reproductive organ


  • single or bifurcated tube
• 3 Classifications of female nematodes

  • oviparous
  • larviparous / viviparous
  • parthenogenic
• oviparous


  producing eggs that develop and hatch outside the body
• larviparous / viviparous


  producing living young larva
• parthenogenic


  • w/o the need for fertilization
  • w/o the need of male adult
• 2 classes of nematodes

  • class enoplea
  • class rhabditea
• class enoplea


  with caudal receptor and caudal gland
• class rhabditea


  with caudal receptor, without caudal gland
• 3 nematodes belongs to class Enoplea


  T - trichuris trichiura

  T - Trichinella spiralis

  C - Capillaria philippinensis
• Based on habitat ---- Small intestine


  C - Capillaria philippinensis

  A - Ascaris lumbricoides

  S - Strongyloides stercoralis

  H - Hookworms
• Based on habitat ----- Large intestine


  E - Enterobius vermicularis

  T - Trichuris trichiura
• common name for Ascaris lumbricoides

  Giant intestinal roundworm
• common name for Trichuris trichiura

  whipworm
• common name for Trichinella spiralis

  trichina worm
• common name for Enterobius vermicularis

  pinworm / seatworm
• common name for Strongyloides stercoralis

  threadworm
• Ascaris lumbricoides


  the largest and most common nematode
• Ascaris lumbricoides


  has terminal mouth with trilobate lips and small triangular buccal cavity
• 3 thick transparent layers----- Fertilized ova


  • vitelline membrane
  • glycogen membrane
  • albuminous mamillary coat