Deadly Poisonous Jellyfish (Documentary)

A look at the rising concern of poisonous jellyfish, from New York's Hudson River, to the beaches of Spain, these animals have become floating deathtraps in the world's oceans, and their population explosion may be the result of mankind's changes to their ecosystems.
Jellyfish or jellies are the major non-polyp form of individuals of the phylum Cnidaria. They are typified as free-swimming marine animals consisting of a gelatinous umbrella-shaped bell and trailing tentacles. The bell can pulsate for locomotion, while stinging tentacles can be used to capture prey.
Jellyfish are found in every ocean, from the surface to the deep sea. A few jellyfish inhabit freshwater. Large, often colorful, jellyfish are common in coastal zones worldwide. Jellyfish have roamed the seas for at least 500 million years, and possibly 700 million years or more, making them the oldest multi-organ animal

Toxicity

Jellyfish sting their prey using nematocysts, also called cnidocysts, stinging structures located in specialized cells called cnidocytes, which are characteristic of all Cnidaria. Contact with a jellyfish tentacle can trigger millions of nematocysts to pierce the skin and inject venom, yet only some species' venom cause an adverse reaction in humans. When a nematocyst is triggered by contact by predator or prey, pressure builds up rapidly inside it up to 2,000 pounds per square inch (14,000 kPa) until it bursts. A lance inside the nematocyst pierces the victim's skin, and poison flows through into the victim. Touching or being touched by a jellyfish can be very uncomfortable, sometimes requiring medical assistance; sting effects range from no effect to extreme pain to death. Even beached and dying jellyfish can still sting when touched.
Scyphozoan jellyfish stings range from a twinge to tingling to agony. Most jellyfish stings are not deadly, but stings of some species of the class Cubozoa and the Box jellyfish, such as the famous and especially toxic Irukandji jellyfish, can be deadly. Stings may cause anaphylaxis, which can be fatal. Medical care may include administration of an antivenom.
In 2010, at a New Hampshire beach, pieces of a single dead lion's mane jellyfish stung between 125 and 150 people. Jellyfish kill 20 to 40 people a year in the Philippines alone. In 2006 the Spanish Red Cross treated 19,000 stung swimmers along the Costa Brava
An Australian box jellyfish called the sea wasp can kill a grown man in a matter of seconds or minutes. Because the harpoons are so shallow, however, Australians have learned that they can protect themselves while swimming in sea wasp waters simply by covering their exposed skin with pantyhose.