Who it gritty, surely all fishermen know. This is a species of worms that live on sandy beaches. That is what their name is due to. This type of worms tends to bury itself in sand mixed with water and silt and stay there almost constantly. The insect almost constantly digs sand. In the sand or on the coast where they live, you can find a large number of passages dug by them. Among fishermen, this type of worm is very popular, as it attracts many species of fish.
Origin of view and description
Peskozhil is a representative of the type of annelid worms, a class of polychaete worms, a family of sandworms, and a species of marine sandbelly. There are several versions of the origin of this type of worms. One of them says that they came from multicellular colonies. Another version says that annelids are descended from free-living flatworms. In support of this version, scientists call the presence of cilia on the body of worms.
It was the worms that became the first creatures on earth to have well-developed, multicellular organs. The ancient ancestors of modern worms came from the sea and looked like a homogeneous, mucus-like mass. These creatures could grow, multiply using the ability to scoop and absorb nutrients from their environment.
Scientists have another theory of the origin of annelids. They could come from animals that, in the process of developing the instinct of self-preservation, learned to crawl, and their body acquired a fusiform shape with two active ends, as well as the abdominal and dorsal sides. Peskozhil is exclusively a marine inhabitant, whose ancestors spread throughout the oceans during evolution.
Appearance and features
Photo: Sand Worm
This type of worm belongs to large creatures. Their body length exceeds 25 centimeters, and the diameter is 0.9-13 centimeters. Worms of this species can have a different color.
It depends on the region of residence:
The body of this creature is conditionally divided into three departments:
- the anterior section is most often reddish-brown. It has no bristles;
- the middle part of a brighter color compared to the front;
- the back of a dark, almost brown color. It contains multiple bristles and a pair of gills that perform respiratory function.
The circulatory system of the sandblast is represented by two large vessels: the dorsal and abdominal. It has a closed type of structure. Blood in sufficient quantity is filled with iron-containing components, due to which it has a red color. Circulation of the blood provides pulsation of the spinal vessel, and to a lesser extent of the abdominal. This type of worms is characterized by a fairly developed musculature. Representatives of the class of polychaete worms move hydraulically by pushing the liquid contents of the body from one end of the body to the other.
The body is divided into segments. In total, the body of an adult worm is divided into 10-12 segments. In appearance, they are very reminiscent of an ordinary earthworm. Both species spend the bulk of their lives in the soil.
Where does the sand dweller live?
Photo: Sandworm Worm
Peskozhil is exclusively a marine inhabitant. Often they can be observed in large numbers in estuaries, bays, in bays or backwaters.
Sandstone geographic regions:
- Black Sea;
- Barents Sea;
- White Sea.
As a habitat, sandworms choose water bodies with salt water. They live mainly on the seabed. Externally, in the habitats of the worm, one can observe moving sand rings located near sand craters. There is practically no oxygen in the sea sand, so the worms have to breathe oxygen, which is dissolved in water. To do this, they are selected on the surface of their tubular houses. Most of the populations of these representatives of flora and fauna live on the coast. It is in the coastal zone for them the most favorable conditions. In some regions, there are huge clusters, the number of which can exceed several tens or even hundreds of thousands per square meter of area.
These creatures live in burrows, the construction of which they themselves are engaged in. Worms are naturally endowed with the ability to secrete a sticky substance using special glands. This ability allows you to connect and fasten the grains of sand that sandblast passes through. Ultimately, they become the walls of this house, or burrows. The hole has the shape of a tube in the form of the letter L. The length of such a tube or tunnel is an average of 20-30 centimeters.
In these tubes, sandguns sometimes spend a rather long period of time with virtually no pain. Scientists say that worms may not leave their shelter for several months. The current brings the necessary amount of food twice a day to the shelter of the sandbags. It is these burrows that are the main defense against numerous enemies. Often in warm weather with the onset of darkness, they can be found in the grass next to their burrows. If there are stones on the sea coast, then under them large accumulations can also be observed.
Now you know where the sand dweller lives. Let’s see what he eats.
What eats sandworms?
Photo: Sea Sandgun
The main source of food is processed, rotting algae and other types of marine vegetation, which sandworms pass through the cavity of their body in the process of digging tunnels. In the process of digging tunnels, representatives of the bristles swallow a huge amount of sea sand, which contains detritus in addition to the sand itself.
Detritus is the organic compound that the worm feeds on. After ingestion, the entire mass passes through the body of the sandblast. Detritus is digested, and sand is excreted by the intestines. To isolate waste and undigested sand, he protrudes the tail end of the body to the surface from his shelter.
In various regions of the habitat of worms, the most diverse soil. The most favorable is muddy and muddy. It is in this soil that contains the greatest amount of nutrients. If these creatures did not swallow such a large amount of sand, they would not be able to separate the necessary nutrients from it with such ease. The digestive system of worms is arranged in the form of a kind of filter that separates unnecessary sand from nutrients.
Features of character and lifestyle
Photo: Sand Worm
Peskozhily often live in numerous colonies. The number of individuals on a small plot of land reaches incredible sizes in some regions. They spend most of their time in their tube-shaped burrows. If a fish begins to hunt for this representative of marine life, he practically sticks to the wall of his shelter with the help of bristles. Peskozhil is naturally endowed with an amazing ability for self-preservation. If you grab him by the front or rear end, he tilts this part and hides in the shelter. Subsequently, the lost part is restored.
Peskozhil large populations leave their tunnels at high tide. Worms lead a burrowing life, digging passages and a tunnel in the sea sand almost continuously. In the process of tunneling, the worms swallow a huge amount of sand, which they actually pass through their entire body. Recycled sand is excreted through the intestines. That is why in places where the worm dug a tunnel, sand embankments are formed in the form of craters or elevations. This is where marine vegetation gets in various ways.
Interesting fact: Scientists conducted a study in which they were able to find out that about 15 tons of sea sand per day passes through the intestines of one individual!
Thanks to the secreted sticky substance, he manages to avoid damage to the intestinal walls. Being in the sand, sandbags provide themselves with food and protection from a large number of enemies.
Social structure and reproduction
Photo: Large Sandblast
Peskozhily belong to dioecious creatures. Nature is designed so that worms, which have a huge number of enemies, can reproduce without compromising the population size. For this reason, reproduction is carried out in water. During the breeding season, small tears are formed on the body of the worms, through which eggs and sperm are released into the water, which settle on the seabed.
Testes and ovaries are present in most segments of the sandbones. For fertilization to occur, it is necessary that male and female germ cells are secreted at a time. Then they settle on the seabed, and fertilization occurs.
The breeding season begins at the beginning or in mid-October and lasts an average of 2-2.5 weeks. After fertilization, larvae are obtained from eggs, which grow quite quickly and turn into adults. Almost from the first days of life, they, like adults, begin to dig a tunnel, which becomes a reliable defense against natural enemies. The average life expectancy of sandbags is 5-6 years.
Natural enemies of the sandboxes
Photo: Sandworm Worm
In natural conditions, worms have a fairly large number of enemies.
Peskozhil enemies in the wild:
- some species of birds, most often gulls, or other species of seabirds;
- some clams;
- a huge number of species of fish of small and medium sizes (cod, saffron cod).
A large number of fish love to eat worms. They pick up the moment when the next portion of sand appears in the form of a crater at the bottom and instantly snatch the worm. However, this is not so simple. With the help of tenacious bristles, he tightly attaches to the walls of his tunnel. In extreme cases, worms are able to recline part of their body. In addition to fish, birds and crustaceans prey on worms in shallow water, or on the coast. They are of great value for fishing enthusiasts.
A man hunts worms not only as bait for successful fishing. Recently, scientists have discovered that his body contains a substance with a pronounced antimicrobial effect. In this regard, today it is the subject of numerous studies and attempts to use in pharmacology and cosmetic medicine.
Population and species status
Photo: Sandblast in nature
In some regions, the number of sandbands is very dense. Their number reaches 270,000 - 300,000 individuals per square meter of territory. In addition, they are very fertile.
An interesting fact: Scientists have established that during the breeding period in the body cavity of one adult individual, about 1,000,000 eggs can develop!
A huge number of worms die as a result of successful hunting of birds, fish, echinoderms, and crustaceans. Another enemy that catches worms in large numbers is humans. It is these worms that are highly valued by fishermen due to the fact that most fish love to feast on them.
They are also sensitive to changes in climatic conditions of the environment. Worms die in whole colonies as a result of environmental pollution. Peskozhil has an appearance very reminiscent of annelids. They have much in common not only in appearance, but also in lifestyle. For such worms, fishermen often come to the coast. They know well how to properly dig and store them, so that fishing is successful.