Difference between annelids and roundworms.

Today, the biosystem of the Earth includes a huge variety of very different animals, including various worms. Each type has its own distinctive features inherent only to it. How do annelids and roundworms differ, for example? Let's try to figure it out.

Roundworms are mainly parasites, that is, they live in the body of their host and feed on it. They are not adapted for life outside a foreign organism, since they have an imperfect structure of their body. Their body is long, not divided into segments, in the form of a very elongated cylinder, narrowed at the tips. As for the muscle tissue, in these worms it is replaced by special longitudinal muscle fibers that allow organisms to move only with the help of flexion. The digestive system has the most primitive form, as it is a tube with mouth and anus. These worms do not need its more perfect form, since the direct process of food digestion occurs in the body of their host.

The structure of the roundworm

Ringworms live in the external environment (soil or water bodies), and feed on organic debris from animals and plants. Their body is shaped like connected segments - rings, which gave them their name. The movement in space of this type of worms is based on the fact that their muscle tissue contracts and relaxes under the influence of peculiar nerve endings. The digestive system has specific parts such as the mouth, esophagus, stomach, intestines, and anus, so that these organisms can live on their own without the help of others. Also, annelids have a simplified circulatory system, manifested in the presence of two large blood vessels and many small branches, and a respiratory system.

The structure of the annelid worm

The difference between annelids and round worms is due to the fact that they belong to two completely different types of these organisms. So, the body of roundworms is a single whole, while in annelids the whole body is divided into certain segments - rings. Thanks to this structure, worms of the second type are able to move without bending, but by contracting and straightening their muscles. In addition, annelids have a more perfect structure of the body, since they have certain rudiments of the respiratory, nervous, digestive and excretory systems.

Conclusions TheDifference.ru

  1. Roundworms live in the host's body, and annelids do not need such a "patron";
  2. In annelids, the trunk is divided into distinct segments, which allows them to move in a different way than roundworms;
  3. Roundworms have an underdeveloped digestive system, and there is no circulatory and respiratory system at all, which cannot be said about annelids, in whose body these systems are present, albeit in a simplified form.