New World tarantulas can be found in the Western Hemisphere, in North, Central and South America. A common trait is their ability to "throw" barbed "hairs" as a defense mechanism, something that their Old World cousins are unable to do. It is thought that this defense mechanism allows these tarantulas a more laid back disposition. Their first reaction is usually not to strike, but to attempt to drive off the intruder through the use of their urticating hairs.
Both Old and New World tarantulas have adapted to their environments and there are species that live in rainforest canopies and arid desert burrows.
In spite of this remarkable adaptability, tarantulas are at risk from habitat destruction and over-collecting. Certain species of tarantulas are even protected by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), which was signed in 1973, which aims to ensure that international trade in specimens of wild animals and plants does not threaten their survival.
More information can be found here: CITES