Many people like to eat hairy crabs, but now many people are afraid to buy dead crabs. So how do you tell if crabs are fresh? It's hairy crabs spitting bubbles!
Hairy crabs spit bubbles, and most people can guess that they are breathing, and it feels more interesting, unlike fish blowing bubbles in water, string by string. There are hairy crabs spitting bubbles on the land!
Hairy crabs spit bubbles because of their unique way of breathing. Hairy crabs are animals that breathe through gills like fish. The difference is that fish suck water into their mouths and then let it pass through their gills. The way hairy crabs breathe is to absorb water from gills and then spray it out from the water outlets on both sides of their mouths.
Hairy crabs are crustaceans that live in water. Like fish, they breathe through their gills, but their gills are somewhat different from fish. They are not born on both sides of the head, but divided into many feathered gills that are loose like sponges, which grow on both sides of the body and are covered with hard head breastplates. When it breathes, it will suck in fresh and clean water from the back of its body. Dissolved oxygen in the water will enter the capillaries of gills, while other water and substances will flow through gills and be spit out from both sides of its mouth. Although hairy crabs live in water, they still have to go ashore for food frequently. Without water, it won't dry, because there is still a lot of water on its cheeks and it can keep breathing. But if you stay on land for a long time, most of the water in your cheeks will be taken away by the air, and your cheeks will gradually dry, so you will feel difficult to breathe. At this time, crabs will still stir their mouths and gills like breathing in water, constantly sucking in air and then spitting out a little water in their gills, forming many bubbles.
So when you buy hairy crabs, you can see if there are bubbles.
Although crabs often live in water, they are different from fish. When living in water, it sucks in fresh water from the back of the body, and the dissolved oxygen in the water enters the blood of the capillaries of the gills and then spits out from both sides of the body. Crabs often climb to the land in search of food, and will not dry up after leaving the water. This is because the crab's gills store a lot of water. Without water, they can still keep breathing, inhale a lot of air and spit it out from both sides of their mouthparts, just like in water. Because too much air is inhaled, the painting area of gills touching the air is very large, and the water contained in gills is spit out together with the air, forming countless bubbles, which accumulate more and more, and many white bubbles are piled up in front of the mouth.
If a crab is caught, it will foam when you catch it. Crab spits bubbles because of its unique way of breathing. Crabs breathe with their gills. Its gills are hidden under the jacket. Like a sponge, it can suck in a lot of water. It lives on land by the water in its gills. After the oxygen is consumed by the water in the cheeks, it will flow back to the body from the bottom of the claws. When water flows through the body, fresh oxygen will melt in. So crabs can breathe in water like fish. But after a long time, the moisture in the cheeks will gradually decrease. At this time, the crab will twitch its mouth and gills in an attempt to absorb water, but it will inhale a lot of air and mix with the water in its gills to form many bubbles.
So when we go to the market to buy crabs, we'd better choose crabs that spit foam, because it shows that they are alive and fresh.