In many sexually mature crab species, the gonads are already developed or nearly so, and they no longer grow during the usual growing season. When stocking crabs in winter and early spring, if mature individuals are accidentally introduced, they often experience high mortality rates during the breeding season, which can lead to significant economic losses. Therefore, it's crucial during the stocking process to carefully identify and remove any mature crabs. There are several reliable ways to determine whether a crab is sexually mature.
First, observe the abdomen of the female crab. In mature females, the abdomen forms a distinct, rounded shape known as an "umbilicus." In males, the reproductive organ, called the transfer device, becomes rigid and takes on a bony, tubular structure, which is a clear sign of maturity. Second, check the male's body for the presence of velvety hairs. In mature males, these hairs are thick, long, and dark in color, indicating that their gonads are fully developed.
Another indicator is the color and texture of the crab’s head and thorax. A normally immature crab typically has a light yellow-colored carapace, while a sexually mature crab exhibits a darker, more intense color—often dark green or blue. Additionally, the surface of the carapace in immature crabs is relatively smooth and flat, whereas in mature individuals, it tends to be more uneven and textured.
Finally, you can open the crab's head and examine the liver area. In female crabs, two purple stripes (ovaries) and developing eggs can be seen. In males, two white masses—representing the testes—are visible, confirming sexual maturity. If only orange-colored liver tissue is present without these structures, the crab is likely still immature.
By carefully observing these physical characteristics, farmers and aquaculturists can make informed decisions about which crabs to stock, reducing the risk of losses due to premature breeding and ensuring better overall productivity.
Spill Control Sandbags
Denilco flood control products are mainly used in municipal management, smart cities, water conservancy and drainage, construction, rail transit, factory property management, and relevant departments of emergency management bureaus;
Water absorbing expansion bag
Denilco water absorbing expansion bag has a wide range of applications and can be used for dam heightening and blockage, water containment and overflow prevention, engineering interception, blockage of hidden ditches and holes, reinforcement of flood control dams at any time, temporary flood control works such as urban waterproof sub embankments and block waterproof walls in flood control and emergency rescue. Before absorbing water, it weighs only 275 grams, and after 2-3 minutes of absorbing water, it can reach 20 kilograms. During emergency rescue, it can replace the soil source and quickly construct rescue projects to reduce losses caused by the lack of soil source on the rescue site and inability to rescue in a timely manner.
Specifications
| Name: Non woven water absorbing expansion ba |
Model： DP400 |
| Brand： DENILCO ® |
Size： 400mm*600mm |
| Color： White |
Outer material：four in one ultrasonic polypropylene non-woven fabric |
| Built in：hydrophilic nanoscale SAP functional materials |
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1. Expansion time: ≤ 3 minutes (water temperature environment ≥ 18 ℃)
2. Pressure resistance strength: ≥ 150 Kg
3. Stacking height: ≥ 1.2m
4. Sealing performance: There is no obvious leakage of water absorbing resin debris before water absorption, and the contents do not overflow after water absorption
5. Drop performance: Free fall from a height of 1 meter to a flat concrete floor without damage
6. Sewing thread body: 100% combed fine cotton thread
7. Product weight: 0.27Kg ± 5% before water absorption, 20Kg ± 5% after water absorption
8. Expansion height: 15cm
9. Usage environment: Freshwater acid-base environment 8>PH>5
10. Product packaging: 50 corrugated cardboard boxes/moisture-proof plastic vacuum bags per box
11. Box size: 42 * 36 * 50cm
12. Gross weight/net weight: 15.5KG/14.4KG
13. Storage conditions: Keep in a dry and cool place
14. Shelf life: 5 years
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Spill Control Sandbags,Absorption Sandbags,Quick Absorb Flood Bags,Sand Bag Dam
Denilco Environmental technology(Suzhou)Co., Ltd. , https://www.wflood.com
