River lamprey belongs to the class of cyclostome fish (Cyclostomata), a subclass of lamprey (Petromyzones). It lives in the rivers. In Russia it has commercial value.
It has an elongated, snake-like body about 40 cm long, covered with mucous bare skin. Its color is dark gray with a metallic sheen. The mouth opening is located in the suction funnel, along the edges of which and on the tongue are teeth. There are no jaws. On the top of the head there is a nasal unpaired opening. She has three eyes, two of which are normally developed, and the third perceives only light, due to the lack of a crystalline lens.
Breathing is provided by seven pairs of gill sacs located along the edges of the body and opening outwards. The skeleton consists of their cartilage. Swims, bending the body, almost like a snake. There are two dorsal fins (less often one), the caudal fin is equally lobed, they are all supported by cartilaginous rays. Paired fins have no river lamprey. The photo shows her well.
River lampreys is divided into passing (inhabiting coastal desalinated areas of the seas and spawning in rivers) and impassable (living in rivers).
Lamprey river - a kind of predator and parasite. It feeds by sucking to aquatic inhabitants, usually fish, drawing flesh and blood from them. She is voracious, in one suction, which can last for many days, she is able to pull much more than her weight from the victim. After such “communication”, many fish die from wounds, since a substance that prevents coagulation gets into their bloodstream.
A year before the lamprey spawning, the river ceases to feed. Significant changes take place in her body: the intestine degrades, the salivary glands die off, the dorsal fins merge into one, the anal fin appears in the female and caviar forms, and in the male, the papilla and milk. The length and weight of both sexes is reduced.
The river lamprey breeds in sections of the river with a fast flow and a pebble bottom, in depth. During the spawning period, the male builds nests by digging holes in the bottom. The female has been floating above him all this time, touching the abdomen of his head, as if cheering. At the very end, it only deepens the hole a little. When the construction is completed, the female sticks to the stone near the nest, and the male sticks to it, gradually moving the suction cup towards the head, and wraps her tail around it. The products of the activity of the gonads they throw out at the same time. After spawning, the couple hides among the stones and soon dies.
Of the eggs, which are more than 20 thousand, after 2 weeks, larvae appear, called butterflies. They look like small yellowish worms. About 4 days they hide between stones at the bottom of the river, and reaching 6 mm in length, burrow into the silt. After 15 days, the larvae leave their place of shelter and swim with the flow, lingering where they can dig into the silt and feed on the remains of algae. The larval stage lasts about 5 years. After metamorphosis, the stage of an adult occurs, during which the lamprey river parasitizes on other river inhabitants.
This cyclostome fish negatively reacts to light. This is the basis of her fishing. Fishermen lower powerful lanterns on both sides of the river so that in the middle there is a dark passage, and they set a trap in it, into which the catch falls.
During this period, river lamprey has excellent taste. And if you consider that there are no bones, bile and intestines in it, then this is an ideal product that can be eaten whole. Before cooking, it is cleaned of mucus and fried on baking sheets, sometimes marinated.
