Shield (lat. triopsidae) refers to small crustaceans, family Notostraca.
Shield and horseshoe crabs are one of the oldest types of crustaceans, they are the oldest extant specimens that have retained their original appearance.
The morphological structure of the shield has not changed for 200 million. years.
The shield is a living fossil that has come down to our days.
The name for the shield was the presence of a shield on the shell, which covers his torso and protects the entire body. Crustacean species include 16 different members of the family. Perfectly adapted to life in fresh, stagnant and flowing water.
On earth, the shield appeared in the time of the dinosaurs. It has a similar structure as that of a horseshoe crab. The main feature of these two ancient representatives of the ancient world is the presence of a strong shield that protects the back.
What does it look like
Up to 10 cm long, body equipped with a wide shell in front and a long thin abdomen. The general shape is similar to the body shape of a tadpole. The surface of the shell is smooth, flattened.
In front is the head, both eyes are located on the top of the head. In the mouth is a pair of manuls that do not have jaws. On the reverse side, the shield has legs, up to 60 pairs. The body is divided into rings. The segments are part of the chest.
Animals have a genital opening on the front of their legs. In the female, it looks like a brood sac. Thus, the legs are needed not only for movement, but also serve as sensory organs. Other rings are combined into the abdomen. The number of rings depends on the species of the crustacean. The abdomen forms a telson and a pair of long thin caudal branches. The shield is brown or grayish yellow in color.
The individual has a small size with a length of 2 to 10 cm.
They are prone to molting and have to shed their shells often enough. With the help of their eyes, they identify food products, as well as a potential partner. Belly color red.
Shields live both in natural conditions and in artificial ones.
The life period is from 1 to 3 months, taking into account if the reservoir does not dry out ahead of schedule.
The shield has four eyes, one “extra” eye recognizes light and darkness and serves as a spatial reference. The purpose of the fourth eye, scientists still have not figured out. The mouth is equipped with large jaws with many teeth.
Males and females have morphological differences, as well as different sizes. Males have an increased shell length, a larger secondary antenna, they use them in the breeding process. Females are equipped with a sac where they lay their eggs.
Africa, Australia, Asia, South America, Europe, Great Britain, some part of America are the environment in which you can meet shield.
Russia and Europe are inhabited by only two of the possible species. In addition to the reservoir, the shield can live in a puddle, ditch, ravine, small pool where there is stagnant water. If the reservoir dries up, the animal dies. If it has time to lay larvae, then under favorable conditions, young individuals will appear from them.
The crustacean has perfectly adapted to life on all continents.
As a rule, shields can be found in a warm reservoir, mainly at the bottom. The preferred temperature ranges from 16 to 30 degrees Celsius. For life, they choose alkaline waters, they tolerate pH less than 6.
During the day, they prefer to burrow into the soil and collect food there. At night they tend to hide in the silt.
Lives exclusively in fresh water. Shield can’t live in the sea.
At home, the shield is kept in an aquarium with fresh water. They are unpretentious, feel good at room temperature, omnivorous. Aquarium food is also suitable for food. The bottom of the aquarium must be equipped with fine sand, which is necessary for their existence and the breeding process. No more than 5 individuals should be placed in one aquarium.
The shield is omnivorous crustacean. Is a predator, can eat animals inferior to it in size and strength. His diet is various larvae and plankton. A favorite of a mosquito is considered a favorite delicacy.
In hungry times, the shield can engage in cannibalism, eat young individuals or their processes on the chest.
Some species eat roots and sheets in plants, such as rice leaves.
The shield is active throughout the day, but it works as efficiently as possible during daylight hours. Sometimes it can be found inverted on the water, while the abdomen will look up.
There is a theory that so crustacean gets food that has accumulated on the surface of the water. Due to the fact that the shield constantly digs in the ground and eats mosquito larvae, it replenishes the supply of nutrients in the body. This fact significantly reduces the number of mosquitoes in ponds.
Shield loner, it can be found separately in the aquatic environment. He cannot live in a large group due to the high level of predation among relatives. With the help of appendages, they can move in a given direction, moving forward. Individuals are in constant motion. They have the same organs as isopods. With their help, they dig in the mud and look for food.
Metabolism declines with the seasons. This happens when the conditions of existence are unfavorable and the available amount of food is not enough to meet the needs.
How it breeds
The shield has several ways of reproduction. Exists:
The female has a special pouch where fertilized eggs fall. In case of favorable conditions, the eggs of the white female are laid on the substrates in the water.
Under adverse conditions, eggs do not hatch until the situation changes for the better. The larval stage of growth is characterized by an orange color of the larva with one eye and three pairs of limbs. In less than a day, it turns into a small shield, similar in appearance to an adult.
The molting period begins and after a week the animal becomes colored as a sexually mature individual, fully capable of reproduction.
In the natural environment, waterfowl eat scutes. In the forest, the forest frog feeds on this crustacean. Shields hunt each other, so they try to live alone.
The brown body protects the crustacean in the water, allowing it to blend in with the color of the ground.
The shield prevents the spread of West Nile viruses due to the consumption of mosquito larvae in large quantities.
Japanese authorities use crustaceans to control weeds in a rice field.
Larger members of the species are often kept at home, placed in a specialized aquarium, where they feed on carrots and shrimp, which is a favorite food in the home.
For a long time on planet Earth, the shield has perfectly adapted to survive in various conditions, so nothing threatens the population. The shield larva easily moves either with the help of animals or with the help of the wind, thereby increasing the scope of distribution.