Perciformes (lat. Perciformes) — a detachment of the class of bony fish. There are over 6000 species and about 150 families. Characteristic features: part fin rays has the form of undifferentiated acute spines, pelvic fins are usually located under the breast and sometimes in front of them; swim bladder not connected with the intestine.
The squad is part of the Perch family (Percidae), with 160 species, many of which have important commercial value. In particular, the Zander (Lucioperca), several species of which live in the basins of the Black and Caspian seas. Some of them live permanently in rivers, others in the seas, others are semi-anadromous fish coming from the rivers into the sea. Perch (Perca) are widely distributed in the rivers and lakes of Russia. Are also objects of the fishery.
The family of Labyrinth fishes (Anabantidae) is a kind of fish, characterized by the presence of saccular outgrowths of the Gill cavities, which are used for temporary breathing air. These fish, such as anabas (Anabas testudineus), often come out to shore and even climb trees. They live in fresh and brackish waters of tropical Africa, Asia and the Islands of the Malay archipelago. Some species, such as gourami, are used as aquarium fish. Continue reading
The ocean abounds with excellent swimmers who, in the words of the famous German nineteenth-century biologist Ernest Haeckel, “free to find their own way”. They can resist the strong current of water and to choose their own way, different from the animals of the plankton. The combination of these actively swimming animals E. Haeckel called the nekton, which means “floating”. Technically, the nekton are aquatic snakes, birds, and animals, but here we will talk only about the two groups of nektonic organisms — the fish and cephalopod molluscs.
Important nektonic animals adaptations to life in the water column of the ocean, according to Professor Yuri Aleev are maintaining the body in a suspended state, creating a driving force, reducing the resistance of the counter flow of water, control the movement of the body, as well as in the ability to disguise and protection. Continue reading
Diversity of fauna, in particular fish, the Volga is considered one of richest rivers. In its pool there are 76 species of fish and 47 subspecies.
The Volga River
The Volga is the largest river in Europe, its length is 3531 km, and the Origins of the river are in the South-West of the Valdai hills, Tver oblast. The river Delta consists of a large number of ducts, Islands, which often are overgrown with reed and cattail. Volga belongs to relatively deep waters. In the upper reaches of the Volga river is a small river with low-lying marshy shores. In the river is very well developed aquatic vegetation, with the exception of some places. Volga has a sandy, silty-sandy and silty soils, in the shallows of the river the soils are gravelly or pebbly.
Fish world of the Volga
The fish living in the river Delta, are very different from each other in size and way of life. The smallest fish of the Volga – grained goby length of 2.5 cm and resembling in appearance a tadpole. The biggest fish of the Volga – the Beluga, the length of which reaches up to 4 m. Continue reading