How to identify the types of sea crabs that are poisonous in Vietnam

To prevent poisoning, people should not eat strange, colorful and unusual sea crabs.
Sea crab is a nutritious dish and is loved by many people. However, besides benign species, many types of sea crabs contain dangerous toxins, especially, they have strange shapes, colorful colors.

According to information from Bach Mai Hospital (Hanoi), Dr. Nguyen Trung Nguyen, Director of the Poison Control Center, said that there are at least 3 types of poisonous crabs: demon-faced crab, seed crab and Florida crab. father in the waters of Central Vietnam, Nha Trang and some other places. Recently, the Institute of Oceanography, Vietnam Academy of Science and Technology, also confirmed that the man in Thanh Hoa was poisoned after eating crab. This type of crab has a very high toxicity, very easily fatal when eaten. Dr. Nguyen said that the crab poisoning progress is very fast, it can appear after eating within a few hours. Many patients eat at sea, on ships, on islands, get poisoned and when they are brought ashore, they cannot be treated in time. Even many cases died on the way to the hospital. Devil-faced crab Devil face crab, scientific name is Zosimus aeneus, is one of the poisonous crab species living in Vietnamese waters, there are many from Da Nang to Vung Tau. Devil-faced crabs are often hidden in shallow, low-tide areas. They have the same color as coral, so it is difficult to identify. According to information from Nha Trang Institute of Oceanography, the devil face crab has the widest chest shell of nearly 90 mm, about 55 mm long. Crab shell has many flat convex, eye-catching colors, unlike food sea crabs. Devil-faced crabs are blue-green with white, brown, and yellow markings. The legs and legs of the crab are dark brown. The crab’s meat, eggs and claws contain the same toxins in pufferfish as saxitoxin, neurotoxin and tetrodotoxin. The poisonous crabs poisonous crabs formed by the main food source are the algae in the coral reef. These substances cause paralysis of the nervous system, inhibiting respiration. This is a very powerful toxin to the nervous system, just 0.5 mg can be fatal for adults. Devil-faced crabs can be fatal when ingested. Photo: Sciencesource. Crab fan This crab species has the scientific name Demania reynaudii of the family Xanthidae (the Xanthid reef crab). According to the literature, the fan crab is a crustacean, benthic, common in coral reefs in the tropical Indo-Pacific. Currently, scientists have identified nearly 300 species of crabs living in the sea, some of which contain the toxin saxitoxin or tetrodotoxin. These are 2 toxins that cause poisoning and death if ingested. According to Associate Professor, Dr. Dao Viet Ha, Director of Institute of Oceanography, Vietnam Academy of Science and Technology, tetrodotoxin is heat-stable and acid-stable so it does not decompose at high temperature when cooking. nine. It can even exist in processed, frozen, canned products. This toxin can affect the central nervous system of humans and higher animals, stopping the transmission of nerve signals. Symptoms of poisoning usually appear about 30 minutes after eating, including tongue numbness, lip numbness, dizziness, headache, abdominal cramps, nausea, vomiting, difficulty speaking, difficulty swallowing, movement imbalance. .. In severe cases, the victim has seizures, froth, coma and death. Demania renaudii fan crab specimen collected from food poisoning in Thanh Hoa on March 27. Photo: Truong Si Hai Trinh. Crab seeds The seed crab (Platypodia granulosa) is just as poisonous as the demon face crab. Crab seeds have oval body. Their nipple shells are semi-circular, the longest about 30 mm, the widest about 40 mm, covered with granular convex tumors. Raw crabs are yellowish-green in color, sometimes yellowish-brown or purplish-red in color. The knuckles are black in color. The seed crab is usually found on living coral reefs, at a depth of about 3 m, at Hon Tam – Nha Trang. They are sometimes mistaken for the common Florida crab (Atergatis floridus). Crab Florida According to the National Institutes of Medicine (NIH), this crab has the scientific name Atergastis floridus. They have an oval body, relatively narrow shell, smooth surface, smooth back. The whole crab body is brown to dark brown in color, with large yellow spots on the back. The Florida crab has a nipple shell that is almost like a horizontal ellipse. The back surface of the crab shell is slightly convex but smooth, making it difficult to identify areas. The toes are dark colored. The crabs are of large, equal and smooth size with a black spoon-shaped head. Male crabs are usually larger than females. The crab shell has a square shape, is quite thick and has a width of 8-10 cm. Florida crabs are usually more active at night. Atergatis floridus occurs in the eastern Indian Ocean, Southeast Asia, Australia, and the western Pacific. According to the Western Australian Museum, The meat of the crab Florida, like many related crabs from the Xanthidae family, is very poisonous. The toxins in this crab species such as tetrodotoxin and saxitoxin are produced by vibrio-like bacteria that live in symbiosis on crabs. These toxins, similar to puffer fish, are a major factor in poisoning cases in shellfish.