Why does the squid squirt "ink"?

Bird squid, also known as "cuttlefish". In fact, it is inaccurate to call the bird thief a fish. Because it is not a vertebrate, but a mollusk. On the contrary, it and the land snails, river mussels, oysters in the sea is "relatives", they belong to the shellfish. Some people can not help but ask: since the squid is shellfish, then why it is not like snails, clams, oysters have the kind of shell? This is due to the habits of the squid and their different reasons. The squid lives in the vast ocean, it is not like other shellfish just grow in the rock, drilling wood or sand, can only crawl slowly. Instead, the squid will use a cone-shaped organ shaped like a funnel under the head, ejected a stream of water, like a fish in the sea as fast as swimming. That's why it doesn't need shells to protect itself; its shells have deteriorated. Squid usually swim in the sea, specializing in small fish, shrimp, etc. for food. But when it encounters fierce fish invasion, it will be in the ink sac sprayed a thick and black toxic ink to the surrounding sea water black, so as to block the enemy's line of sight, paralyze the enemy, and take the opportunity to escape. This shows that the squid spraying ink is a way to protect itself and escape from enemies. Qingming, rain, summer, it is the time of the south wind blowing, squid in groups from the ocean migrate to our coastal cliffs, reefs and beaches to spawn, the entire sea surface dyed black, which is the cuttlefish season, is a large number of our fishermen fishing season. As early as in ancient times, China's ancient books on this habit of squid has also been described: "this fish meet fishing boats that spit ink dyeing water to black to mix its body, fishermen see the water black is known to be the net of a big catch." It can be seen that our country's diligent and brave fishermen have long been familiar with the squid can spray ink of this habit, and use this knowledge to catch squid. As the saying goes, "three mountains, six waters, one field". It can be seen that the waters are vast and the fishery industry has great potential. China's coast, especially the coastal areas of Zhejiang is a natural spawning ground for squid. Our fishermen can catch a large number of squid from the coast every year. Squid meat is very delicious, in addition to fresh food, but also can be made into dried squid, exported abroad. Squid ink sac in the ink after processing can be made of printing ink. Squid bone can be used as industrial raw materials and medicinal raw materials. The ink sac itself is also a valuable medicinal herbs. So, squid is a treasure.

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