Nematodes: Its Characteristics and Threat as Parasitic Worms
Nematodes are commonly known as Roundworms which belongs to the Phylum Nematoda with estimated 500 000 species. The name was derived from Greek term Nematos which means thread. Nematodes which are the common name for phylum with unsegmented-terrestrial marine or freshwater worms; they abound in the surface layers of soil that very abundant and widely distributed. One of the few examples of nematodes is Ascaris, hookworm; filarial worm and pinworm.
They live in great numbers in a diverse environment –in freshwater, in soil, in saltwater and in the bodies of plants and animals. Nematodes have economic and medical harm as they are considered parasites on living plants, animals and even to man. Getting infected by these parasites are frequently unnoticed that sometimes may cause malignant diseases.
Phylum Nematoda: Roundworms
- Threadworms belong to the genus Ascaris.
- Ccommon worm of puppies is classified as Toxocara canis.
- Eelworms belong to the genus Heterodera,
- Earcockle of wheat belong to the genus Tylenchus,
- Trichina worm belongs to the Trichinella spiralis
Characteristic of Nematodes
They have approximately 12,000 known species of roundworms, but plenty remains unknown and suspected just like Gordian worms as a subclass. They are cylindrical, tapering animals with naïve bodies that consist of an interior gut and a muscular outer wall that is separated by a fluid-filled cavity called pseudocoel. Its outer wall produces an elastic cuticle that is molted 4x during the life of the animal. Most of the nematodes range from microscopic about 10 centimeters and 4 inches long.
Nematodes just like sponges, cnidarians are regularly hermaphroditic and fertilization occurs internally. They also resemble without metamorphosis. Of all parasitic worms the easiest nematodes to find is Ascaris in the slaughterhouse of pigs. Ascaris lives in big numbers in the intestine of pigs. Male is smaller than female Ascaris and the female posterior is straight while the male posterior is bent.
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All about Ascaris
Ascaris has a scientific name of Ascaris lumbricoides. And the one that lives on man intestine is called hominis and in pigs is suis, but if this kind of lumbricoides enters the human body, healthy person is not affected but those who suffers malnutrition is susceptible to this parasite.
Ascaris body shape is like a tube most specifically long and rounded. Their body movement whips by curving their bodies from back to front or vice versa. One of the good examples of this is vinegar eel which lives on vinegar with a scientific name Turbatrix aceti.
Ascaris is commonly known as round worms often affects children since they are less careful in their health habits. A female ascaris can lay eggs as much as 200,000 eggs a day inside a host intestine. These eggs are thrown by the body with undigested food and feces/poop. Outside the body of the worm the egg undergo some development and the eggs that starts to develop are could embryo. These eggs of Ascaris are called “embryonated eggs”
The feces or waste matter that was infected by Ascaris eggs may pollute the soil and the embryonated eggs may spread by the wind, insect or animals and may rise up in the levels food chain. Some eggs may get by children who plays on the ground and some are get if they don’t wash their hands before eating.
The worst thing, the embryonated eggs of Ascaris hatch in the intestine of the new host. The young or larvae which emerge from the eggs penetrate the wall of the small intestine and enter the blood vessels, from there; they are carried by the blood streams to the liver, the heart and then the lungs.
In the lungs, where there is plenty of air, the larvae undergo further development. From there they climb the windpipe up to the throat. Once they reach the throat, they are swallowed again by the host. When they reach the small intestine again, they complete their development and become full grown worms.
Effects of Ascaris to Man
- Inflammation of the lungs.
- Highly susceptible to infection by other parasites
- May get sick like pneumonia.
- Intestine and abdomen of the host may to become distended which is accompanied with pain
Measures against ascaris infection
- Sanitary waste disposal
- Washing hands before eating
- Keeping food away from lies
References; Science and Technology by Lilia M. Rabago Ph. D , Crescensia C. Joaquin Ph.D, Catherine B. Lagunzad , PH. D, Encarta, Encyclopedia