Anatomy Of Roundworm

The nematode body is cylindrical elongated and smooth with no limbs protruding such as is seen in the common garden worm though generally on a smaller scale. Like tardigrades they have a reduced number of hox genes but as their sister phylum nematomorpha has kept the ancestral protostome hox genotype it shows that the reduction has o.

Roundworms

Roundworms usually range in size from 2 inches in length to microscopic.

Anatomy of roundworm. Whereas the rest of the body is bilaterally symmetrical the head is radially symmetrical with sensory bristles and in many cases solid head shields radiating outwards around the mouth. Roundworms are one of the simplest animal groups that have a complete digestive system. They are a diverse animal phylum inhabiting a broad range of environments.

Even though they are thin and round they are actually bilaterally symmetric. Roundworms come in segmented and unsegmented parasitic and nonparasitic varieties. The flatworm has a gastrovascular cavity with only a single opening that functions as both mouth and anus.

Roundworms are psuedocoelomate which means they have a body cavity between their mesoderm and endoderm layers. Longitudinal canals that function as the excretory system of the roundworm releasing nitrogenous wastes in the form of ammonia and urea pseudocoelom body cavity lined on the inside by a layer of gastrodermis and on the outside by a layer of mesoderm. It is cosmopolitan in distribution but abundant in tropical countries.

The roundworm has a complete digestive tract with two separate openings for the mouth and anus. Also called nematodes roundworms are highly diverse cylindrical shaped worms that live in a wide array of terrestrial and aquatic environments. Taxonomically they are classified along with insects and other moulting animals in the clade ecdysozoa and unlike flatworms have tubular digestive systems with openings at both ends.

Since roundworms have no respiratory or circulatory systems they use diffusion for respiration and circulation of substances around their body. The body is contained within a tough elastic cuticle which in many species forms elaborate structures useful for identification. Ascaris the round worm ascaris lumbricoides is known as roundworm that is commonly found as intestinal parasite in vertebrates like man pig cattle etc.

Posterior end of male is. These muscles are all aligned longitudinally along the inside of the body so the nematode can only bend its body from side to side not crawl or lift itself. Morphology ascaris is a cylindrical worm white to light pinkish in colour tapering at both ends.

The cuticle is the closest thing a roundworm has to a skeleton and in fact the worm uses its cuticle as a support and leverage point for movement. Long muscles lie just underneath the epidermis. Female measures 30 40 cm and male 15 30 cm.

The nematodes or roundworms constitute the phylum nematoda. The mouth has either three or six lips which often bear a series of teeth on their inner edges.

Chapter 36 Flatworms Roundworms And Rotifers