Ascaris is a cyllinderical psedocoelomate nematode worm. It is a round worm.
Systematic Position:
Phylum – Ascheliminthes
Class – Nematode
ADVERTISEMENTS:
Sub-Class – Phasmideaa
Genus – Ascaris
Species – lumbricoides.
Habit and Habitat:
ADVERTISEMENTS:
A Lumbricoides is a nematode parasite in the small intestine of children then the adult. It has holozoic nutrition and takes hosts digested food by sucking action. Respiration is an aerobic. The worm produces antienzymes to counteract host’ this enzyme.
Morphology:
Ascaris shows karked sexual dimorphisom. Female is larger (40 compound in lentgh) than male (30 compound in length). The posterior end of the female is straight but in male it is curved end two copulatory spicules protrude from the slit-like opening.
The colour of the animal is reddish yellow. There are four longitudinal lines- one mid dorsal, one mid ventral and two lateral in position. The mouth is situated at the anterior end of the body and guarded by there lips, one dorsal and two ventrolateral. The dorsal lip has a circule of four sensory papillae and the remaining two lips have two rows of sensory papplae.
ADVERTISEMENTS:
Each sensory structure is called amphid. In nematodes, amphids are useful in identification and classification of species. The sensory papillale are tangoreceptors and amphids are chemoreceptors. The posterior end of the male bears 50 pairs pre-anal papillae in front of the cloacal aperture and 5 pairs of post-anal papillae behind it. The first two pairs post-anal papillae are double.
These papillae of the male help in copulation. An excretory pore is located mid-ventrally a little behind the mouth. A genital pore is present only in female in the mid-ventral part of the body. Anus is present only in female. But in male cloacal aperture is present midventrally infront of curved end of the body. The chitinous penial spicules protrude through the cloacal aperture. Both male and female reside in the hosts’ intestine where copulation takes place. The embryo develops into rhabditiform larva.