Читать книгу Extreme Nature - Mark Carwardine - Страница 22

NAME	box jellyfish Chironex fleckeri
LOCATION	near-shore waters of parts of Australia and South-east Asia
ABILITY	causing excruciating pain and possible death

© Valerie & Ron Taylor/ardea.com

Some say this is the world’s most venomous animal, but this depends what you mean. Is it the venomous creature you are most likely to encounter, does it kill more people than any other, or are the chemicals most toxic? Certainly, a single box jellyfish contains enough venom to kill at least 60 people, and many do die after being stung.

Though the jellyfish has no desire to kill humans, it is a hunter. An adult box jellyfish – as large as a human head, with tentacles up to 4.6m (15ft) long – has a full array of powerful stinging cells, called nematocysts, and hunts mainly fish. It is very active (unlike many other jellyfish) and jet-propels itself through the sea in search of prey. It’s also transparent, ensuring that fish (and humans) don’t spot its deadly tentacles.

There are four bundles of about ten tentacles, most over 2m (6ft 6in) long and each carrying around 3 million nematocysts. The toxin contains chemicals that affect heart muscle and nerves and destroy tissue, the purpose being to kill a fish quickly so it doesn’t get away. But if a box jellyfish encounters a human, it may also sting in self-defence. The pain is excruciating, and without anti-venom, a victim can die from heart failure in just a few minutes. In addition, nematocysts fire not just on command but when stimulated physically or chemically. Strangely, they can’t penetrate women’s tights, and until ‘stinger suits’ became available, lifesavers patrolling beaches would wear tights unashamedly.