Most of the terrestrial invertebrates found in the Galapagos have their origins in the dry coastal regions of South and Central America. The main methods of dispersal to the islands are likely to have been rafting and transport as aerial plankton. As with other groups of plants and animals, some species have a worldwide distribution and some are endemic.
Among the most interesting species of terrestrial invertebrates in the Galapagos are the spiders. There are over fifty species of spider here. Many of them are widely distributed; few are endemic. In the picture at left, we have one of the most beautiful Galapagos spiders: the star or spiny spider, Gasteracantha servillei. This species has a hard, shell-like and spiny abdomen that dwarfs the rest of the body. Perhaps the formation of spines serves as protection against birds. In most spider species, the males are especially minute. In this species the dramatically sculptured abdomen is bright yellow and black. They are found commonly in mangroves and other shore vegetation near lagoons and are also found up to the humid zone.
