Dangerous Animals

Updated February 21, 2017 | Factmonster Staff

Fascinating but Deadly
Sharks, snakes, sea wasps, and blue-ringed octopuses

by David Johnson


Sharks are one of nature’s most perfect hunting machines. But despite publicity, shark attacks on people are extraordinarily rare. According to the International Shark Attack File, there have been just over 2,000 confirmed shark attacks in the whole world since 1580. Most victims survive. For more information, read shark facts and the shark hall of fame.

More than 80% of all snakes are not venomous.

There are 2,700 species of snakes in the world, including about 250 in the U.S. More than 80% of all snakes are not venomous. Only about 400 are poisonous at all, and only about 50 present a real danger to humans. Most poisonous snakes in the New World belong to the pit viper family, including the bushmaster, copperhead, fer-de-lance, rattlesnake, and water moccasin. Two species of the coral snake, which belongs to the viper family, are also found in the U.S. They rarely bite unless touched. Thousands of people around the world, especially in the tropics, die of snakebites each year.

Blue-Ringed Octopuses

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    Swimmers sometimes touch or pick up the blue-ringed octopuses they find floating in the waters off Australia. The blue-rings sometimes bite people, but so gently that victims frequently don’t even realize it. But minutes later, numbness, muscular weakness, difficult breathing, vomiting, hallucinations, and even respiratory failure begin to set in. The salivary glands of the octopus contain bacteria that produce tetrodotoxin (TTX), one of the most lethal natural toxins known. One milligram of TTX can kill an adult human in ten minutes by shutting off oxygen to the brain. Since there is no antidote, artificial respiration and other life-support measures are offered. If a victim survives 24 hours, full recovery is usually expected.

    TTX is also found in the Japanese puffer fish, California newts, some Central American frogs, a type of sea star, a species of horseshoe crab, and several varieties of snail and worm. TTX is believed to be an ingredient in the preparation used in Haitian and West African voodoo to create zombies.

    Sea Wasps

    The sea wasp is a type of jellyfish found in the ocean off Northern Australia. It has a body as large as a basketball and tentacles 15 feet long. Thousands of tiny stingers along the tentacles can kill a human in minutes if a sting is left untreated. In the past century, more swimmers, 65, have been killed by sea wasps than Great White sharks.

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