Department of Zoology at ANDC/Zoology Museum/Museum specimens/Nemathelminthes/Ascaris

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Ascaris lumbricoides

Date & Time : 27, February 2024 03:04

Ascaris lumbricoides

Systematic Position

Phylum: Nemathelminthes

Class: Phasmidia

Genus: Ascaris

Species: lumbricoides

Common Name: Giant Round worm

Habit and habitat

Ascaris is an endoparasite and lives in the small intestine of man.


Ascaris lumbricoides is one of the most common nematodes distributed throughout the world affecting more than one billion people. These are more prevalent in areas with warm and moist climates. Infection is most common in tropical and subtropical areas especially in areas with poor sanitation and hygiene. Though, it is very common in India, the incidence of infection is the highest in Korea and Phillipines.

Identifying Features

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  • Body is elongated, cylindrical and pointed at both the ends.

  • Body surface is marked with 4 longitudinal lines namely - mid-dorsal line, mid ventral line and two lateral lines.

  • Mouth is provided with two types of lips; median dorsal lip, and submedian ventral lips.

  • Lips have special sensory receptors called papillae and amphids. These are chemoreceptive in function which detects the chemical nature of food.

  • Sexes are separate and sexual dimorphism is well-marked.

  • Male has three openings while female has four openings.

  • Male has a pair of penial setae arising from its cloaca.

Ascaris lumbricoides1

Ascaris lumbricoides - Male and Female

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Web Resources

Video: - This video describes life cycle and pathogenicity of Ascaris lumbricoides in detail. It will clarify all the queries of the learner.

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Case Study
Endoscopy showing Ascaris lumbricoides in duodenum

A 34 year old female resident of rural China complaint of nausea, vomiting, vague abdominal pain and fever. Doctors performed an upper endoscopy and found a live Ascaris in the second portion of the duodenum. The roundworm was retrieved using a basket and once secured, both worm and endoscope were removed from the patient. The length of the organism was about 20cm in total, and it exhibited continued movement.