The opuntia cactus is a prickly pear variety that is endemic to the Galapagos. Six species of opuntia have adapted into fourteen varieties and provide food and nesting habitat. To prevent extinction from hungry tortoises, the opuntia in this photograph evolved into a tree-like plant. Look closely and you will see a bird perched on top. On islands where there are no tortoises the opuntia cacti are shorter.