Desert tortoise. View of a desert tortoise (Gopherus agassizii) walking through flowers. These tortoises live in the south-western USA and northern Mexico, on dry ground with tough plants and cacti. They are only active at dawn and dusk due to the extreme temperatures in this region. They eat mainly succulent plants. To escape from the lethal heat, they dig special burrows, which consist of a long tunnel leading to a spacious chamber. The flowers seen here are desert dandelions. Photographed in the Joshua Tree National Park, California, USA.