Nematodes have slender, elongated bodies that vary in size from 0.2 mm to over 1 meter long. They are generally bilaterally symmetrical and colorless. While their bodies appear unsegmented, some nematodes have a segmented appearance due to their cuticle. The body can be divided into head, tail, and four longitudinal zones. The head contains mouth structures while the tail varies in shape between species.

1. Morphology of nematode
HPP-5221 , 2(1+1)
Nematode pests of horticultural
crops and their management

2. Body shape and size
• Slender, elongated, spindle shaped or fusiform organisms.
• Majority of species the two sexes look alike, although the
males are generally slightly smaller than females.
• Sexual dimorphism occurs in some members of Tylenchida,
where female become swollen and male are vermiform
within the same species e.g.: Anguina, Meloidogyne,
Heterodera, Rotylenchulus and Tylenchulus etc.

4. • Their size may vary from 0.2 mm (Pratylenchus) to about 12
mm (Paralongidorus spimikis).
• Their width range from 0.01 to 0.5 mm. in some cases body
width may be less than 1% of its length, e.g. Ecphyadophora
or as mush as 15 % e.g. Criconema.
• The free living non parasitic nematodes are generally larger
while the largest animal parasitic nematodes may have a length
of some centimeter to a meter or more.
• Whale fish parasitising: 27 feet long

6. Body posture
• The nematode when relaxed by gentle heat, either lie straight
(Pratylenchus) or slightly ventrally curved (Hoplolaimus) or
curved in ‘C’ shape (Tylenchorhynchus) or form a spiral
(Helicotylenchus).
• The curvature of the body is always towards ventral side
except in case of Dorsalla which curved in a ‘C’ shape
towards dorsal side.

7. Segmentation, colouration
and symmetry
• Non segmented.
• Appearance of segmentation in some nematode: cuticle e. g.
Croconema.
• Generally nematodes are colorless or whitish with slight
yellowish tint depending upon the chemical composition of
cuticle.
• Basically the nematode body is bilaterally symmetrical

8. Body regions
• Nematode body is tubular without any distinction of regions.
However, for the sake of convenience, the anterior end bearing
mouth, lips and stoma is referred as „Head’ and the region
beyond the anus is rightly termed as „Tail’.

9. Variation in tail terminal

10. Body regions

11. • Longitudinally, the nematode body is divisible in to four
zones; the ventral bears the openings of digestive (anus),
excretory (excretory pore), and reproductive (vulva,
cloacal aperture) systems; the side exactly opposite to the
ventral is dorsal.. The other two sides located at right
angles to the dorsal and ventral sides are right and left
laterals.