jueves, 14 de mayo de 2009
Scorpions are members of the class Arachnida and are closely related to spiders, mites, and ticks. They are commonly thought of as desert dwellers, but they also live in Brazilian forests, British Columbia, North Carolina, and even the Himalayas. These hardy, adaptable insects have been around for hundreds of millions of years, and they are nothing if not survivors.
There are almost 2,000 scorpion species, but only 30 or 40 have strong enough poison to kill a person. The many types of venom are effectively tailored to their users' lifestyles, however, and are highly selected for effectiveness against that species' chosen prey.
Scorpions typically eat insects, but their diet can be extremely variable—another key to their survival in so many harsh locales. When food is scarce, the scorpion has an amazing ability to slow its metabolism to as little as one-third the typical rate for arthropods. This technique enables some species to use little oxygen and live on as little as a single insect per year. Yet even with lowered metabolism, the scorpion has the ability to spring quickly to the hunt when the opportunity presents itself—a gift that many hibernating species lack.
Such survival skills allow scorpions to live in some of the planet's toughest environments. Researchers have even frozen scorpions overnight, only to put them in the sun the next day and watch them thaw out and walk away. But there is one thing scorpions have a difficult time living without—soil. They are burrowing animals, so in areas of permafrost or heavy grasses, where loose soil is not available, scorpions may not be able to survive.