Friday, February 24, 2012

Spiders

Almost all spiders possess venom, which may inject into their prey through sharp, hollow fangs. Few spiders are able to pierce human skin, but about 30 species out of a total of about 40,000 can cause severe illness or even death if they bite people. However, spiders are not usually aggressive and have rarely been drawn to bite unless it is provoked. The very notorious spider is undoubtedly America’s Black widow. Although its fangs are very short, it manages to get them through the skin to inject venom which is volume for volume, about 15 times more poisonous than rattle snake venom. The spider obviously injects a much smaller amount than a rattle snake but it causes severe pain and nausea, and has resulted in many deaths over the centuries. The closely related red widow in habits the sand pine scrub of southeast Florida. Similar spiders are found in southern Europe as well as in most other warm areas of the world.


The brown recluse spider from the southern USA injects venom that destroys blood and other tissues. It has caused some deaths. The Sydney funnel web is Australia’s deadliest spider, and is particularly dangerous because it often makes its home in gardens. The most deadly South American spider is the wandering spider an aggressive hunter that has been known to kill children. It occasionally turns up elsewhere, having travelled in crates of bananas. Its fangs are over 400 long but the longest fangs –up to 12mm long- belong to the bird eating spiders or tarantulas. Luckily, these big spiders do not have particularly strong venoms. Antivenins are now available to treat victims of most of the dangerous spiders. Provided they are given quickly they should result in almost immediate recovery.