What is the most poisonous animal in the sea for humans?

The Pufferfish, the Australian Box Jellyfish, and the Stonefish are extremely poisonous marine animals – so toxic that they can kill a human within minutes. But which one is the most poisonous?

There are several species of Pufferfish in the Tetraodontidae family. The majority of Pufferfish are toxic and some are among the most poisonous fish in the world. They are poisonous if eaten because the tetrodotoxin is found in their liver and sometimes in their skin. 

For humans, the tetrodotoxin in Pufferfish is 1,200 times deadlier than cyanide. In one Pufferfish, there is enough toxin to kill 30 adult humans. There is currently no antidote – no cure for the poison. The Pufferfish is an expensive meal in Japan and chefs are trained to remove the toxic parts of the fish.

However, the Pufferfish is not the most poisonous fish in the world. The most venomous fish is the Stonefish. The Stonefish in the Scorpaenidae family has dorsal fins (back fins) with 13 sharp spines. Each spine has two venom glands. The Stonefish looks like a rock or coral, and if humans step on a Stonefish, the spines release toxin which is extremely painful. There is an antidote for the Stonefish poison if it is administered quickly. 

The most poisonous animal in the sea is the Australian Box Jellyfish (Chironex fleckeri) in the Chirodropidae family. The box-shaped, or cube-shaped Box Jellyfish has about 15 tentacles, each up to 3 metres (10 feet) long. Each tentacle is covered with millions of cnidocytes. 

If a tentacle touches a human, the cnidocytes release microscopic darts with extremely powerful venom. There is enough venom to kill 60 adult humans. The person will die in 2 to 5 minutes of cardiac arrest (heart attack) or drowning. If the poisoning is not extensive, there is an antivenom to treat the poison. 

Photographer: Martina Nicolls and Stonefish, SeanMack

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