Cancers . These bespozvonochnyh, living in the rivers, lakes, estuaries, ponds, other reservoirs, many know very well. Cancers have got such popularity for high flavouring and nutritious qualities of meat. It contains approximately 16 percent of fiber and is easily acquired. Cancers together with interiors not used in food go on preparation of valuable broths, cancer oil, powders; spirit infusions of cancers were since ancient times used in national medicine for treatment for a malaria, rheumatism and some other illnesses. In food meat of claws, pads, a paunch, and also a liver - yellowish-green weight inside golovogrudi is used. However, in a cancer everything is edible, except an armour and an intestines.
Cancers live in the pure water well enriched by oxygen. They leave dirty water, and there is no place if to leave, perish. Increasing concentration began to affect their number last years in water of various industrial wastes, herbicides and other chemicals strongly all. At all stages of life cycle of cancers predatory fishes destroy: a catfish, nalim, a pike, a perch, a pike perch and others. Cancers fall prey of many birds, especially herons, ducks, and also mammals: muskrats, rats and others.
To Live, under some data, cancers can in favorable conditions: shirokopalyj - till 20-25 years, dlinnopalyj - till 40-50 years. polovozrelymi cancers become already on the third year of a life at achievement of length not less than 7-8 Pairing see occurs usually in September - October and even in November, and sometimes and in the winter at a water temperature of 13-15 degrees and more low. One male impregnates some females. Fruitfulness of cancers depends on their age and the size. On the average each female can bring posterity in 300-400 rachkov. In two-three weeks after fertilisation the female postpones caviar under a paunch for further vynashivanija. Berries are attached to belly legs. That to caviar fresh water, a female all time constantly arrived moves with a paunch and pads. Vynashivanie calves lasts about seven months. Usual time when there is an exit molodi - the end of May - the beginning of June when the water temperature reaches 21-23 degrees. Newborns rachki by means of the claws keep on pleopodah mothers. In a half-month, month they, as well as adults, start to conduct an independent way of life, with each moult increasing in sizes. The firm armour is necessary to a cancer for protection against enemies - big and small. However the hardened armour does not allow, to a cancer to grow. Therefore, having saved up a certain stock of substances, for the further growth, cancers periodically dump old armours. Young do it more often, old - is more rare. The moult period - the hard time for a cancer for at this time it cannot move and becomes an easy mark of enemies.
The New armour is formed for 10-15 days, and approximately in a month it gets the usual durability.
Cancers concern omnivores. Having good sense of smell, they easily find to themselves food if that is available nearby. Eat larvae of insects, frogs, fish and other water inhabitants. They eat patients or snulyh fishes, for as have nicknamed cancers river hospital attendants. Into their diet enter as well many water plants. Especially they love rdest, haru, water grechihu etc.
Cancers slowly Grow. For two years of a life reach 6 6,5 sm, for five years - 9-10 sm, for ten years - approximately 15 Males dlinnopalyh cancers by forty years of a life see 30-35 sm and weights - to 250 g can reach, females - 18-28 sm and weights - till 150 Catch cancers various tackles. On pure, with light water, sites of the rivers and reservoirs in warm summertime of cancers catch hands - in coastal holes, under stones, in a grass. Divers in sports masks get them from depth of 2-3 m. Unfortunately, among such rakolovov not too there are not enough people who injuriously destroy ikrjanyh the females preparing for a moult, and faded cancers that it is impossible to do.
Other Crustacea . To each fisher, probably, will learn reasonably interestingly that all zooplankton more than for 90 percent on number and weight consists of Crustacea. They live in all hydrosphere, even in small pools, in soil, underground, cave and the more so in the big surface water - the rivers, lakes, ponds.