Many modern people like crayfish very much. When summer comes, we will eat delicious sesame seeds and feel very comfortable. However, many people may think that eating crayfish is a special hobby of modern people. After all, crayfish is an exotic species. It raged in the country of origin, but it became delicious in China. But recently it was found that lizards ate ancient crayfish 654.38 billion years ago. What's going on here? Did lizards like crayfish 100 million years ago?
1. Rare samples of stomach contents
165438+1October19th, a group of Chinese and foreign scientists announced in Beijing that they had discovered a rare specimen of stomach contents for the first time in Jianchang county, Liaoning province, which is of great significance for people to understand the predation habits of small and medium-sized reptiles in Cretaceous. The research was led by Xing Lida and Liang, associate professors of China Geo University, Niu Kecheng, executive director of the Museum of Natural History, and Susan Evans, a professor at University College London. The research paper was published by Elsevier Publishing Group in Cretaceous Research.
Stomach contents are very rare and important fossil records, which are the direct evidence of people's understanding of ancient biological eating habits. This specimen was found in Jiufotang Formation of Lower Cretaceous in Lamadong area, Jianchang County, Liaoning Province. This is an interesting Sagittarius specimen, which contains the stomach contents of undigested crustaceans. It is now in the newly opened Liang Museum of Natural History.
Sagittarius is the first lizard named after the world-famous Jehol biota. Widely distributed in Yixian Formation and Jiufotang Formation of Lower Cretaceous. Sagittarius is often found with wolf fin fish, water turtles and various insect fossils. Fossils were first discovered and named by Japanese scholars. The specimens were lost in War of Resistance against Japanese Aggression, including three species: stout Sagittarius, young Sagittarius and double-headed Sagittarius. According to the analysis of body length and bone morphology, the new specimen should be classified as young Sagittarius, with a nose and buttocks length of 22 cm.
Previous Sagittarius fossils recorded fish fragments in the stomach, while large crustaceans were discovered for the first time. The collection of this specimen in Liangtong Natural Museum is in an unfinished state. The contents of the stomach are gradually exposed under the exquisite cleaning and repairing technology of the technicians in the fossil mineral crystal cleaning and repairing laboratory of the museum. The pliers of this large crustacean are covered with tiny particles on the back, slender fragments of the chest and feet, mouthparts and broken tentacles, all of which are consistent with Saunders'.
The crayfish we often eat is scientifically called Procambarus clarkii, which is native to the Gulf of Mexico and the north shore of Louisiana, so some people call it "Louisiana crayfish". Later, it was introduced to China and became a popular sesame because of its edible value. A large number of freshwater crayfish fossils were found in the Jehol biota in China. About 65.438+0.3 billion to 65.438+0.2 billion years ago, researcher Shen of Nanjing Institute of Paleontology studied these specimens, speculating that crayfish originated in East Asia and then spread to Central Asia, Europe and North America.
According to Xing Lida, the length and proportion of crayfish fragments found this time tell us that the prey of ancient crayfish is about 12 to 13 cm, which is a very rich meal for this Sagittarius. Interestingly, Sagittarius lacks crustacean fragments in its stomach, so this little lizard may have preyed on an ancient coral that is molting by the river. "According to all the records of stomach contents, we still think that Sagittarius has the habit of preying on river banks, although it lacks obvious swimming morphological characteristics."
2. crayfish
Lobster Procambarus clarkii: also known as Procambarus clarkii, red lobster and crayfish. It looks like a shrimp with a hard shell. The adult is about 5.6~ 1 1.9 cm long, dark red, with a nearly black carapace and wedge-shaped stripes on its dorsal abdomen. The body of young shrimp is uniform gray, sometimes with black ripples. The pliers are long and narrow. The middle part of crustaceans is not separated by gaps in the grid space, and crustaceans are obviously granular. There is a side thorn or notch at the end of the blade.
This kind of freshwater economic shrimp is popular because of its delicious meat. Because of its omnivorousness, fast growth and strong adaptability, it has formed an absolute competitive advantage in the local ecological environment. Food intake includes aquatic plants, algae, aquatic insects, animal carcasses, etc. When food is scarce, they also kill each other. In recent years, crayfish has become an important economic species in China. In the process of commercial farming, especially in the inaccessible ecological waters, escape should be strictly prevented. It has caused devastating damage to the ecological competitive advantage of local species.
3. Main value
look
Because most crayfish are very resistant to pollution, they can still survive in water containing highly polluting toxins. Stocking in the aquarium can also effectively remove fish manure and moss, which is of great help to improve the hydrological environment.
nutrition
Crayfish has high protein content, soft meat and easy digestion. This is excellent food for people who are weak and need to take care of after illness. Shrimp is also rich in magnesium, zinc, iodine and selenium. Magnesium plays an important role in regulating heart activity, protecting cardiovascular system, reducing cholesterol content in blood and preventing arteriosclerosis. At the same time, it can dilate coronary artery, which is beneficial to prevent hypertension and myocardial infarction. Lobster contains astaxanthin, which is a strong antioxidant. Scientists at Osaka University in Japan have found that astaxanthin helps to eliminate the "jet lag" caused by jet lag. In addition, crayfish can also be used as medicine, which can eliminate phlegm and relieve cough, and promote wound granulation healing after operation.
menu
Crayfish is popular because of its large size, rich meat and delicious meat, and has been made into many dishes.
Braised Prawns
spicy crayfish
Shisanwei small lobster
Fresh shisanwei small lobster
spicy crayfish
Pixian small lobster
spicy crayfish
Fried crayfish
Lamimi crayfish
Garlic crayfish
Curry crayfish
Beer crayfish
Braised crayfish
Fried lobster with garlic
Chilli shrimp balls
Taste shrimp
select
Crayfish washed with shrimp powder usually look clean and have bright colors. However, the claws of corroded crayfish are easy to fall off. If the number of crayfish and shrimp tongs on the table is generally small, it is more likely to use shrimp washing powder. Therefore, crayfish falling from pliers should be carefully eaten.
To know whether crayfish live in clear water, we should first look at its back, which is red, bright, clean and white, and then turn it over to see the fluff on its stomach and the silky hair on its claws. If it's white and neat, it's basically grown up in clear water.
After all, crayfish are aquatic animals and will eat dead humus. Moreover, bacterial toxins only accumulate in the body, so people try to buy crayfish that have just grown up. Pay attention to the skin color when buying: the old lobster is red, black or red, and the young and strong lobster has a natural and healthy luster. Then touch the shrimp shell with your hand. Hard and old, elastic, like nails, just grew into a shell. Try buying soft-shelled crayfish.
Most restaurants serve crayfish. Before eating crayfish, it is best to look at its body: if its tail is curly, it means that it was alive before being put into the pot. If the tail is straight, it means that he died before entering the jar. Moreover, the lobster head is easy to absorb heavy metals and bacteria, so it is best to turn it when eating.
Self-made crayfish, it is recommended that crayfish be soaked in clear water for 2~3 hours, washed clean and cooked at high temperature before eating.
Because of the high content of protein in crayfish, the decay of protein will do great harm to human health, so it is best to cook crayfish before eating. Don't eat too much crayfish, because too much protein can also lead to indigestion.