Mantis shrimps are resistant to desiccation. At a relative humidity of 94% and an air temperature of 20°C, they can stay exposed for nearly 14 hours.
Mantis shrimps are dioecious and have morphological differences. The male mantis shrimp has a pair of slender intercourse organs on the inside of the base of the eighth thoracic limb. The female has a pair of spawning holes on the ventral surface of the sixth thoracic segment, and a "king"-shaped hole on the ventral surface of the 6th to 8th segments. The color of colloid glands tends to be milky white as the individual matures.
The annual reproductive cycle of female mantis shrimps is divided into five stages (1) immature stage (August to September); (2) development stage (October to November); (3) pre-maturity stage (December to December) February); (4) Maturity period (3-5 months); (5) Egg-laying period (6-7). Similarly, male shrimps are divided into (1) immature stage (July); (2) development stage (August to September); (3) pre-mature stage (October to December); (4) mature stage (January to April) ); (5) Sperm discharge period (5-6 months).
During the spawning season, shortly after the male and female mantis shrimps mate, the female mantis shrimp begins to lay eggs. After the eggs are laid, they are held on the sixth to eighth segments of the chest. They usually lie on their backs against the cave wall on the back of the abdomen and outside the abdominal limbs to lay eggs. Each egg laying lasts about 3 hours. After spawning, a large number of individuals die. Mantis shrimp eggs are oval-shaped, and the hatching of fertilized eggs takes 1 to 2 months at 21 to 28°C. Within the appropriate temperature range, the higher the temperature, the shorter the hatching time. The planktonic larvae after hatching are divided into eleven stages. In the first two stages, they rely on their own incubation nutrition and do not feed. In the third stage, planktonic larvae begin to feed on Artemia larvae of suitable size. In the later stages, the larvae tend to be benthic. After eleven stages of metamorphosis, the juvenile mantis shrimp behaves similarly to the adult mantis shrimp and needs to live in a cave.
The growth of mantis shrimp is discontinuous, and its growth must be completed through molting. The length of the adult grows in a stepped manner as the shell is molted.
The growth of mantis shrimp has obvious seasonal changes, with the fastest growth rate from late summer to late autumn. Analyzing the relationship between the growth of gonads and body and food intake, the life cycle of mantis shrimp can be divided into four stages: (1) Molting growth stage (August to November) (2) Overwintering stage (December to February); (3) Gonad growth and maturation stage (March to May); (4) Egg laying and sperm ejaculation stage. It is generally believed that the life span of most mantis shrimps is 2 years.
Temporary fattening technology for mantis shrimp
(1) In addition to the conditions of the breeding pond, in addition to being constructed according to conventional fenced breeding ponds, the temporary breeding pond for mantis shrimp requires the tide level to be from the upper section of the mid-tide zone to the high tide The lower section of the area is better, with an area of ??about 5 acres, and the maximum should not exceed 10 acres. There is no limit to the depth of the pond water. It can be used for dry pond farming or water storage farming. The water storage depth is preferably more than 0.5 meters, and the substrate is mainly sandy. And it is soft, making it easier for mantis shrimps to burrow and hide. The fenced ponds that have been cultured should be desilted, tidied and disinfected. To facilitate fishing. A collection pit should be dug at the lowest part of the fenced breeding pond and a cage-shaped mesh bag should be laid.
Source and stocking of seedlings
1. Source of seeds. Currently, artificial propagation and cultivation of mantis shrimps are being researched and explored. The seedlings used for temporary cultivation come from small-sized mantis shrimps caught manually on natural tidal flats. The general size is 100 to 200 individuals/kg and the length is 3 to 5 cm. The shrimps are required to have strong bodies, hard shells, strong vitality, complete swimming limbs and walking legs, healthy and disease-free, no damage and neat specifications. The best mantis shrimps used for temporary breeding should have 1 to 2 black spots on the body, that is, black Spot-mouthed mantis shrimp. If there are no black spots on the body and the mantis shrimps in the White Sea area are caught with a net, the survival rate during the temporary breeding process is very low, so they are not suitable for temporary breeding.
2． Stocking time. According to the habit of mantis shrimps having two breeding periods in a year, namely spring breeding and autumn breeding, there are two temporary breeding periods for mantis shrimps, namely spring and summer temporary breeding and autumn temporary breeding. Generally, the spring stocking time is from April to June. , The autumn stocking time is from August to September.
3． Stocking density. The stocking density of mantis shrimps depends on the size of the seedlings, stocking season, feed conditions, water quality conditions and the living habits of the mantis shrimps. If it is too dense, holes and cannibalism will easily occur; if it is too thin, it will affect the economic benefits of the breeding pond. Generally, mantis shrimps with a size of 4 to 5 centimeters can be stocked at a rate of 3,000 to 5,000 shrimp per acre, or 20 to 35 kilograms. Because mantis shrimps are good at drilling holes, they generally cannot be mixed with shellfish to avoid affecting the normal growth of shellfish.
Feeding and management
1. Feed feeding. Mantis shrimps are omnivores and like to eat small fish, shrimps and various low-value shellfish with high protein content in natural waters. Common baits include clams (sea melon seeds), clams (humpback clams) and low-value fish, shrimps and crabs. The amount of feeding should be determined according to the mantis shrimp's feeding status, bait quality, quantity of residual bait, water temperature, tide, water quality, weather conditions and the activity and growth of the mantis shrimp. If you feed small miscellaneous fish and shrimp, it is generally 5% to 10% of the body weight, and check their feeding status frequently. If you feed sea melon seeds, since they can live and grow naturally in the sea area, you can feed more appropriately. If the bait allows , can also be fed once every few days. According to the mantis shrimp's habit of hiding during the day and coming out at night and drilling holes to lurk after low tide. Generally, feeding is done twice a day, once in the morning and once in the evening. The amount of feeding is more in the evening than in the morning, and more is fed when the tide is high, and no or less is fed when the tide is low. The feed should be fed evenly on the entire beach to prevent the mantis shrimps from gathering together to fight and kill each other when feeding, and at low tide, the mantis shrimps drill holes and lurk to compete with each other for territory, which affects growth and survival rates.
2． Water quality management. Due to the living habits of mantis shrimps and the water level in the fenced breeding ponds flowing in and out with the tide, water quality management is not as strict and important as that of shrimp farming. Generally, the spring tide can store water and dry the pond with the rise and fall of the tide, or every few days. The dry pond is once a day to improve the conditions of the substrate. The small tide water is generally used to store water to prevent the long-term dry pond from affecting the feeding and activities of mantis shrimps.
3． Prevent massacres. Mantis shrimps are aggressive and cannibalistic, especially when they are shedding their shells and lurking in holes. Therefore, the first step is to separate the breeding ponds with nets and ditches; the second step is to feed enough and evenly to ensure that every mantis shrimp can eat and eat well; the third step is to arrange the stocking reasonably density.
Harvest artificially raised mantis shrimps. When the mantis shrimps grow to 20 to 40 shrimps/kg, the muscles of the individuals are plump, and the female individuals are thick, they can be harvested. The fishing method is generally at the gate or collection pit. Fix the net cage bag in the middle, use the low tide to release the water, and the mantis shrimps will enter the net cage bag with the current for fishing. In this way, through several rising tides, basically 80% to 90% of the mantis shrimps will be caught. Finally, they can be caught directly from the breeding tidal flat by hand. . Special attention should be paid to the fact that mantis shrimps begin to enter the overwintering dormant stage in November, that is, they burrow into the mud for 20 to 40 centimeters without moving on the surface. Harvesting at this time will increase labor intensity, otherwise it will have to wait until next spring. Therefore, when and how to harvest should be considered during temporary breeding.