To prevent poisoning, people should avoid eating strange-looking, brightly colored sea crabs that have unusual shapes.
Types of Poisonous Crabs in Vietnam
Sea crabs are a nutritious dish loved by many. However, alongside benign species, many types of sea crabs contain toxins that pose significant risks, especially those with strange shapes and vibrant colors.
According to information from Bach Mai Hospital (Hanoi), Dr. Nguyen Trung Nguyen, Director of the Poison Control Center, stated that there are at least three types of poisonous sea crabs: the Devil Face Crab, Fan Crab, and Florida Crab, found in the coastal regions of Central Vietnam, Nha Trang, and several other locations.
Recently, the Institute of Oceanography, Vietnam Academy of Science and Technology, confirmed that a man in Thanh Hoa was poisoned after eating a Fan Crab. This crab has very high toxicity and can easily lead to death if consumed.
Dr. Nguyen noted that the onset of sea crab poisoning is very rapid, potentially occurring within a few hours after consumption. Many patients who ate crabs at sea, on boats, or at islands experienced poisoning and could not be saved by the time they reached the shore. In fact, several cases have resulted in fatalities on the way to the hospital.
Devil Face Crab
The Devil Face Crab, scientifically known as Zosimus aeneus, is one of the poisonous crab species found in the waters of Vietnam, ranging from Da Nang to Vung Tau. These crabs typically hide in shallow waters and tidal zones. Their coloration closely resembles coral, making them difficult to identify.
According to the Institute of Oceanography in Nha Trang, the carapace of the Devil Face Crab can reach a maximum width of about 90 mm and a length of approximately 55 mm. Their shells are adorned with flat, protruding bumps and vibrant colors that set them apart from edible crabs. The Devil Face Crab is characterized by a bluish-green hue with white, brown, and yellow spots, while its legs and claws are dark brown.
The meat, eggs, and claws of the Devil Face Crab contain toxins similar to those found in pufferfish, such as saxitoxin, neurotoxin, and tetrodotoxin. These toxins are produced from their primary diet of algae found in coral reefs. They can cause paralysis of the nervous system and suppress respiratory function. This is an extremely potent neurotoxin; as little as 0.5 mg can be lethal to an adult.
Devil Face Crab can be lethal if consumed. (Photo: Sciencesource).
Fan Crab
This species is scientifically known as Demania reynaudii, belonging to the Xanthidae family (Xanthid crabs). According to literature, the Fan Crab is a benthic crustacean commonly found in coral reefs within the tropical Indian and Pacific Oceans.
Currently, scientists have identified nearly 300 species of Fan Crabs living in the sea, some of which contain deadly toxins such as saxitoxin or tetrodotoxin. These two toxins are known to cause fatal poisoning in humans if ingested.
According to Associate Professor Dr. Dao Viet Ha, Director of the Institute of Oceanography, Vietnam Academy of Science and Technology, tetrodotoxin is heat-stable and acid-stable, meaning it does not break down at high cooking temperatures. In fact, it can persist in processed, frozen, and canned products.
This toxin can affect the central nervous system of humans and higher animals, halting the transmission of nerve signals.
Symptoms of poisoning typically appear about 30 minutes after consumption and include tingling of the tongue, lips, dizziness, headaches, abdominal cramps, nausea, vomiting, difficulty speaking, difficulty swallowing, and loss of motor balance. In severe cases, victims may experience convulsions, frothing at the mouth, coma, and potentially death.
Specimen of Fan Crab Demania renaudii. (Photo: Truong Si Hai Trinh).
Granule Crab
The Granule Crab (Platypodia granulosa) is also as poisonous as the Devil Face Crab. It has an oval body shape. The carapace is semicircular, measuring up to 30 mm in length and 40 mm in width, covered completely with granule-like protrusions.
Live Granule Crabs are typically dark green with a yellowish hue, sometimes brownish-yellow or slightly reddish-purple. The segments of their pincers are black. This type of crab is often found on living coral reefs at depths of about 3 meters near Hon Tam – Nha Trang.
They are sometimes mistaken for the commonly seen Florida Crab (Atergatis floridus).
Florida Crab
According to the U.S. National Institutes of Health (NIH), this crab species is scientifically known as Atergastis floridus. They have an oval body shape, relatively narrow carapace, and smooth surface with a glossy back. The entire body is colored from brownish-green to dark brown, with large yellow spots on the back.
The Florida Crab’s carapace is nearly elliptical in shape. The dorsal surface is slightly convex but smooth, making it difficult to identify specific regions. The pincers are dark in color.
These crabs have large, equal-sized pincers with spoon-shaped black tips. Males typically have larger pincers than females. The carapace is square-shaped, quite thick, and measures 8-10 cm in width. Florida Crabs are generally more active at night.
Atergatis floridus is found in the eastern Indian Ocean, Southeast Asia, Australia, and the western Pacific Ocean.
According to the Western Australian Museum, the meat of the Florida Crab, like many related species from the Xanthidae family, is very toxic. The toxins in this crab, such as tetrodotoxin and saxitoxin, are produced by vibrio bacteria that symbiotically live on the crab. These toxins are similar to those found in pufferfish and are the primary factors related to poisoning cases in shellfish.
- 13 Survival Tips Everyone Should Know to Help You Escape Danger in a Pinch
- Only 4 Countries Produce This “Super Small” Component Found in Ballpoint Pens, Which is Made of Material Twice as Hard as Steel!
- The Most Venomous Snake in China: 1 Milligram of Venom is Enough to Kill a Person, Even the King Cobra Fears It
