Nemertine is a worm, a tape-like type. Creatures of this category do not have external organs of touch. However, at the same time, they are able to get food in a rather original way - by “shooting” at the prey with an abundance of mucus, which is secreted by a long proboscis, which goes deep into the body of the creature.
What is the way of life of the represented animals? What does a nemertine (worm) look like? We will consider photos and descriptions of such reptiles later in the article.
History of the discovery of nemertine
For the first time, the existence of nemerteans was discovered thanks to the discovery made by the scientist G. Barleyz. In 1758, a researcher identified a worm of this type in sea waters, described its morphological structure, and even created an image of the animal.
Encyclopedic knowledge about nemerteans expanded significantly in the 19th century. Many zoologists have brought to science new, interesting information about these unique animals that live mainly on the seabed. Making discoveries in the presented area became possible due to the emergence of technical means for working at depth. During this period, it was proposedthe very definition of "nemertina".
The Soviet zoologist N. A. Livanov was actively involved in the study of nemerteans. In 1955, he proved that these animals are a transitional branch between flatworms and tapeworms. Prior to this, such creatures were classified as annelids.
Appearance
A typical representative of nemerteans has a body elongated in the anteroposterior direction, somewhat flattened in the dorsal and abdominal sections. The body length of individual representatives varies from a few millimeters to tens of meters. However, measuring the real size of nemerteans is complicated by the fact that these creatures are able to stretch like leeches.
Nemertine is a worm whose body is divided into the trunk and head sections. The border between these areas is the cervical groove. The head of the animal contains a mouth opening. The trunk section has no pronounced external organs. On the sides of the body, only small sex glands stand out. At the back of the worm is a well-defined anus.
The skin of nemerteans is capable of producing a significant amount of mucus. Therefore, most worms of this type look unattractive to predators. Numerous marine specimens are brightly colored, which is a warning signal of danger to potential enemies in their natural habitat. At the same time, there are enough representatives of whitish nemerteans. Some of them have translucent skin, through which the internal organs are visible.
Food
Nemertine is a worm that has an elongated tubular mouth opening. Inside the mouth apparatus contains a special proboscis, which folds deep into the body cavity and is located above the internal organs when the animal is resting. During the hunt, this plastic tube unfolds and is thrown out by the worm in the direction of the victim under the influence of hydraulic pressure. The prey is covered in sticky, thick and acrid mucus.
How does a nemertine eat? The worm can swallow the immobilized victim whole or divide it into parts. Some animals of this type envelop prey in a cocoon of mucus, leaving it in reserve.
Internal structure
Nemertine is a worm that does not have a body cavity as such. All gaps between the internal organs are filled with a binding tissue - the parenchyma. The entrails are represented by the posterior, middle and anterior intestines.
Nemerteans have the most developed circulatory system among all tapeworms. As for the respiratory organs, such animals do not have them. Saturation of cells with oxygen occurs through its entry through the skin.
The nervous system is built on the principle of an orthogon. In other words, nerve cells form specific fibers, and these are assembled into nerve trunks.
Classes
The following classes of nemertines are distinguished:
- Anopla - the so-called unarmed worms. A distinctive feature of the creatures of this class is the absence of a proboscis inoral cavity. Food is taken in through an opening in the abdomen. A prominent representative of this class is a giant sea nemerte called Lineus Longissimus, whose body length can reach up to 30 meters with a width of not more than one centimeter.
- The nemertine worm, class Enopla, has a proboscis at the front of its body. The latter is thrown out, hitting the victim with several stilettos and wrapping it in thick mucus. Representatives of this class are distinguished mainly by their modest size.
Lifestyle
Most of the worms that are classified as nemerteans are bottom-dwelling marine animals. However, quite a lot of species of freshwater creatures of this type are known. There are also single land representatives of nemertines.
Nemertine is a worm that leads a predatory lifestyle. Some animals of the presented type do not hunt on their own, but are scavengers. There are also known nemerteans that parasitize in the mantle cavity of marine molluscs. Currently, there is a detailed description of about 1,200 species of these worms.
