In this article, we will introduce you to roundworms, which, unlike flatworms, have a body cavity. This species has a cavity between the wall of the body and the intestine.
Type roundworms. Classes
Roundworms are bilaterally symmetrical and are invertebrate animals. Now there are more than thirty thousand species that form four classes:
- hairs;
- abdominal
- nematodes;
- rotifers.
Roundworms are common everywhere, throughout the globe, and very often they can be seen as parasites in animals, plants and humans. Now let's take a closer look at each class of roundworms.
Hairs
This class of roundworms is distinguished by the fact that the larvae lead an exclusively parasitic lifestyle. They got this name because of the hairy body. They are white to brown. Body length - up to forty centimeters, while the thickness does not exceed five millimeters. Note that females have a larger body in length than males.
The nutrition of roundworms of this class is characterized by the fact that adult individuals are generally not able to swallow food. Their throat is a lump of cells.
The full cycle of hair development takes eighteen months. Adult individuals (females) lay up to a million eggs, of which larvae emerge within a month. Their main goal is to get into the host’s body, where they can penetrate even with food. If the owner does not fit, then the worm waits until its owner is eaten by another predator.
When the owner is "approved", the hairy begins to develop rapidly. If the worm reaches its peak of development, then it leaves the body (by drilling the host’s body), and, as a rule, the host dies.
Abdominal
These are very small representatives of this type. The body of round belly worms is only one and a half millimeters in length. Now more than two hundred representatives of this class are known. They move with the help of cilia, which sometimes form whole bundles located on an elongated or bottle-shaped body. In order to be able to temporarily attach to the substrate, there are tubes on the body (at the rear end). The entire surface of the body, including the cilia, is covered with a cuticle forming on the upper part of the scale. The primary cavity of a round worm of such a class as abdominal, is very weakly expressed.
The mouth is at the front end of the body. The nutrition of roundworms of this class is carried out using bacteria. The pharynx works like a pump, the cilia create a stream of water that is directed into the oral cavity.
As for reproduction, along with dioecious forms, hermaphrodites are also found. Fertilization is internal, the genitals lie in front of the anus.
Nematodes
This class leads both a free and a parasitic lifestyle. The variety of roundworms (nematodes) is more than a million species. Free-living live both on land and in water, with over one million individuals per cubic meter. These species play a very large, significant role in ecosystems. But many representatives of this class lead a parasitic lifestyle, causing diseases of plants and animals, including humans. The nutrition of roundworms (nematodes) is limited to algae and bacteria, in the case of a parasitic lifestyle - nutrition at the expense of the host.
In plants, parasites cause damage to stems, roots, fruits, leaves, and in humans - various types of invasive diseases. Most commonly found in people:
- roundworms;
- pinworms;
- trichinella;
- hookworms;
- rishta and so on.
Treatment consists in ridding, expelling these parasites from the host body by various methods.
Nematodes in humans
To begin with, how roundworms can enter the human body. Firstly, this is nutrition: there are a great many roundworms, and if hygiene rules are not followed, then these parasites enter our body through dirty food or water. It is also possible infection through an insect bite or through the skin. The most dangerous insect that most likely could award you with worms is a mosquito. And through the skin, parasites enter if there is an open contact of the earth and blood (for example, when cut).
How to understand that you have parasites? The primary symptoms are itching in the anus, vaginal pain, impaired stool and appetite, and vomiting is possible. At the initial stage, it is necessary to get rid of extra guests who can subsequently seriously affect your health.
Rotifers
Let's move on to the last class of roundworms. To a greater extent, this class leads a free lifestyle in fresh water, but is found in the seas and in moist soil. Despite the fact that the majority leads a free lifestyle, parasites are found. The peculiarity of the rotifers is the presence of legs and fingers. This is a muscular growth of the body that helps to move.
As for development, in favorable conditions in the population only female individuals are observed, which, through parthenogenesis, produce only their own females. As soon as there is a threat (for example, drying out of ponds or freezing), males come to the rescue, with the help of which females can lay winter eggs.
Surprisingly, females can do without sexual reproduction for tens of millions of years.