How do crabs breed the next generation? They rely on the mother crab to give birth to small crabs, and every time the mother crab will lay a large number of eggs, the number can reach more than one million. After these eggs hatch in the abdomen of the mother crab, the larvae can leave the mother and float around with the coastal current. After molting several times, it grows into a big-eyed larva, and after molting several times, it grows into a young crab. The appearance of a young crab is almost the same as that of an adult crab, and it becomes a crab after molting several times. Most sea crabs are directly discharged into the sea without hatching after their eggs mature. River crabs grow in fresh water and breed in seawater. After crab seedlings enter fresh water, they usually live in rivers and lakes with rich bait for about 18 months, and their gonads gradually mature. Mature river crabs begin to lay eggs near the sea where seawater and fresh water are mixed in late autumn and early winter, which is reproductive migration. After mating, the female crab can lay eggs soon, and the eggs attach to the abdominal hair of the female solution and accumulate in the abdomen until the larvae hatch. This kind of crab is called "egg crab". River crabs can lay tens of thousands to millions of eggs at a time, and can lay 2-3 times. In nature, it takes 4 months for fertilized eggs to appear, and the hatching rate can reach about 90%. The newly hatched larvae are very small and shaped like water fleas, called flea larvae. After molting for five times, the flea larvae grow into crab larvae (megalopa) in about 35 days, and the crab larvae molt again to become young crabs. The newly shelled crab is called soft-shelled crab, which can't eat and defend against the enemy. It takes 1-2 days for the shell to harden gradually, and then it moves gradually, and the crab body increases obviously after shelling. After breeding, crabs will soon age and die. References:
National Bureau of Coordination /...ge%3D9% 3d9 Portunus trituberculatus breeding habits (representing sea crabs) Portunus trituberculatus is bisexual. The average life span is 2 years, rarely more than 3 years. The smallest in biology is the head breastplate, which is 5. 1 cm long, and the largest in males is the head breastplate, which is 1 1 cm wide and weighs 7 10/0g. The largest female is the head breastplate, which is 10.5cm long, 22cm wide and weighs 730g g. The spawning population is mainly composed of 1-2-year-old parent crabs. Females die after spawning and hatching. Males can die 2-3 days after mating. The mating time of wintering Portunus trituberculatus is July to August every year, and the mating peak of one-year-old Portunus trituberculatus is 9-65438+ 10.
How do crabs mate?
Similar to goldfish, they don't mate. After the female crab lays eggs, the male crab sprays * * *. . After fertilization, the mother crab hides her eggs in her stomach. Directly hatch out. . .
How do hairy crabs breed?
First, whether cultivating crab species or cultivating crabs, we must first choose good fry, which is the key to successful breeding. There are two kinds of crab seedlings: artificial breeding and natural catching. The naturally captured crab seedlings have complex sources, many parallel imports, high value and many uncertain factors. One advantage of artificial propagation of crab seedlings is that the size of parents can be strictly controlled, thus ensuring the purity and survival rate of the propagated crab seedlings, and the price is only about half of that of natural crab seedlings. Considering all kinds of factors, it is more economical to choose artificial crab seedlings. Second, use high-quality full-price granular materials special for hairy crabs. Compared with traditional feeding methods such as wheat and corn, using high-quality whole-grain feed has the following advantages: 1. Feeding is convenient. 2. Strong palatability, not easy to pollute water quality. 3. The breeding benefit is obvious. If you really can't buy the full-price pellet of hairy crabs, you can make your own feed, but you must add the elements of shrimp and crab shelling. Third, strengthen feeding management. 1. Reasonable feeding amount and feeding time. The feeding amount at different growth stages is different, and the daily feeding amount should be increased or decreased according to the water temperature of the day and the feeding situation of the previous day. Feed should be placed on the soil slope near the water surface or in shallow water near the pool, and the feeding time can be chosen every evening. 2. Do a good job in water quality control and regulation. (1) quicklime is often used to adjust water quality and keep water fresh. (2) The water level in the crab pond is maintained at 0.6 ~ 1 m in spring, and can reach 1 ~ 1.5 m in summer. (3) When changing water, the difference between the internal and external water levels should not be too high, and it is best to keep a slight running water all the year round. 3. Do a good job of patrolling the pond. Once a problem is found, measures must be taken immediately. I hope to adopt satisfactory answers and comments.
How to breed crabs correctly
(1) Breeding of Eriocheir sinensis
In order to improve the survival rate of young crabs and increase economic benefits, crabs should be raised first. At present, in order to make the big-eyed larvae reach the commercial crab, most of them adopt temporary rearing technology in plastic greenhouse. Choose one with good water quality and sufficient water resources; Note: The pond with convenient drainage, no water leakage, no water seepage and little silt should not be too large, the water depth should not exceed 1.2m, the east-west direction of the pond is good, and the sunshine is sufficient. Please refer to the construction method of agricultural vegetable greenhouse for the construction of greenhouse.
15- 20 days before the crab seedlings are released, 75 kilograms of quicklime should be sprinkled on each mu for disinfection. After the medicinal properties disappear, it is necessary to feed water with an 80-mesh sieve to cultivate basic bait, transplant aquatic plants (which must be strictly disinfected), and set up necessary escape prevention facilities. Crab seedlings can be shallower when they enter the pool. Conducive to improving the water temperature and the growth of algae and aquatic plants in the water. Feed bait 2-3 times a day, such as soybean milk, fish, shrimp paste, etc. , and feed in the surrounding shallow waters, and feed at 4% of the body weight, and always pay attention to the weather, water quality sanctions, individual growth, and the number of organisms competing for food. With the growth of young crabs, we should also add some plant bait, such as duckweed and other high-quality aquatic plants. In daily management, we should pay attention to water quality regulation, grasp that water quality should be fat and cool, change water frequently, and change water less, so as not to cause drastic changes in water temperature and water level. After about 2 months of cultivation, crabs can be detained.
(2) Adult crab culture
Adult crabs like the clear and transparent water environment, rich in aquatic plants and rich in bait, which is most suitable for the growth of river crabs. At present, it is mostly cultivated in ponds, lakes, rivers and rice fields. Now give priority to with the pond for a brief introduction:
1, pond conditions
Clay, sandy soil or sub-sandy soil with sufficient water, convenient water intake and drainage, good water pollution and good ventilation are beneficial to the growth and reproduction of aquatic plants, benthic insects, snails and water worms. The old pond should be thoroughly dredged, the silt should not exceed 20cm, and the pond area should not be too small. The water depth of the pond is kept at about 0.6- 1.5m all the year round, and varies from place to place, with the shallowest point 10cm. Several mounds slightly above the water surface can be built in the pond, that is, crab island, where aquatic plants can be transplanted. The pond should not be too steep, and the slope ratio is generally below 1: 1.5, otherwise the river crabs will grow easily. You can also build artificial caves.
2. Transplant aquatic plants
The natural yield of Eriocheir sinensis mainly depends on the number of aquatic plants and benthic organisms (bait organisms) in the waters. In the process of aquaculture, it is an indispensable technical measure to plant aquatic plants well. Planting aquatic plants can not only feed crabs and supplement vitamins for ten days, but also support fighting and concealment, which is a powerful measure to improve the survival rate of river crabs in various periods. In addition, it can absorb harmful ammonia nitrogen, carbon dioxide and organic matter in the pool, release oxygen and stabilize water quality. The masses often say that "the size of crabs depends on aquatic plants." Therefore, river crabs cultured in ponds should make great efforts to plant aquatic plants. Our aquatic plants mainly include duckweed, red duckweed, water hyacinth, water hyacinth, black algae, Ceratophyllum, Sophora alopecuroides, water peanuts and so on. Attention should be paid to disinfection and prevention when transplanting.
3. Escape prevention facilities
Escape prevention facilities mostly use plastic film, but also useful cement board, depending on their own situation.
4, pond cleaning and disinfection
Generally, the pond is disinfected with quicklime half a month before the seedlings are released, and the dosage is 75 kg per mu. On the one hand, it can kill pests, on the other hand, it can improve the bottom of the pond, increase the content of calcium ions in the water and promote the molting growth of Eriocheir sinensis. Fertilize in time after receiving water to cultivate algae and basic bait, and the transparency is generally maintained at 40-50 cm. If tadpoles or frog eggs are found, they should be taken out in time to avoid competing for food and hurting young crabs.
5, put the seedlings
Crab seedlings produced in the Yangtze River system are the best seed selection, requiring neat specifications, complete steps, strong physique, active crawling and no injuries.
Sowing and density, pay attention to temperature difference when sowing. Fish fry bought from other places can't be directly put into the pond. They should be soaked in water for 2-3 minutes, taken out and put into the pond 10 minute, and repeated for 2-3 times. Young crabs gradually absorb enough water, adapt to the water temperature, and then put them into the pond, which can improve the survival rate.
Density: At present, it is mostly polyculture, especially polyculture of fish, shrimp and crab, which will bring higher economic benefits. The density can be controlled within 1500 crabs/mu, and the specification is120-150 crabs/kg. If the conditions are poor or shrimp farming is the main thing, the amount of seedlings released can be reduced appropriately.
6. Daily management
(1) Feeding: The whole process of intensive culture in ponds mainly depends on artificial feeding, so the type, quality and quantity of feed have great influence on the growth and development of river crabs. We should adhere to the principle of reasonable collocation of fine, green and coarse, with animal concentrate accounting for 40% and water ...
Crabs raised at home, want to know how to breed? Thank you.
First of all, eggs are attached to the genitals of female crabs, which is the first thing we peel off when we eat crabs. When the eggs hatch, they will live alone without their mother. Small crabs have to molt several times to look like adult crabs. At first, it looked a bit like a lobster. . . .
When is the annual breeding season for crabs?
Mature Eriocheir sinensis began to lay eggs in the offshore area where seawater and fresh water are mixed in late autumn and early winter, which belongs to reproductive migration.
Reproductive ability of hairy crabs
Crabs have strong reproductive ability, generally spawn large eggs, and species that protect eggs from hatching have strong reproductive ability.
Crab is a decapod crustacean with about 4,700 known species. Most species are not uncommon.
In Bao Pu Zi Deng She, Jin Ge Yi called the crab a heartless son. What you see may be feces.
How many eggs a crab lays depends on the specific species, and different kinds of crabs vary greatly.
Just touching its eyes won't reduce its vision.