The Inconspicuous Killer: Box Jellyfish
The sting of Box jellies, also known as “sea wasps” can result in excruciating pain and are incredibly dangerous. There are 3 out of the 28 species that can kill an adult human. These jellies have up to 15 tentacles that are lined with thousands of nematocysts that eject paralyzing venom, and can be as long as 3 meters. Once the victim has been punctured cardiac arrest ensues and the venom starts digestion of the tissue. Depending on the magnitude of contact and the maturity of the jellyfish death can occur within minutes.
Other species may have a less painful sting, but can cause Irukandji syndrome which will settle in up to half and hour after an encounter. This syndrome results in nausea, headache, sweating, cramps, difficulty breathing, and eventually heart attack if left untreated. Since Box jellyfish have the ability to swim and actively seek out their prey they are not considered true jellyfish. Interestingly, they have three eyes that can form images, however since they have no brain it is unclear how they process them.
Beware of Box jellyfish off the northern coast of Australia and other areas of the Indo-Pacific. Research has shown October through May to be the time when the jellies are most numerous near the coastlines. Often times red warning flags will be posted and beaches will be forced to close after any sitings. In the past century there has been almost 70 deaths due to jellyfish stings. To prevent being stung stay within the protective nets, wear stinger suits, or avoid the water all together. If stung, the best immediate treatment is vinegar which blocks the remainder of the nematocysts from firing.
Photos:
http://openwaterpedia.com/images/e/e1/Box_jellyfish.jpg
Information used from:
http://www.jyi.org/issue/the-box-jellyfish-australias-other-marine-killer/