Succulent or Thorny deserts and semi-deserts are restricted in their occurrence to parts of the Americas, Africa, Madagascar and south Asia. They have a sparse cover of typical cactus-like plants and other slow-growing spiny and succulent species, on stony low-nutrient soils. Many of these plants store water in their stems and have deep roots. Short-lived plant species emerge after rains from dormant organs or soil seed banks. Plants and animals tolerate extreme summer temperatures and mild winters. Nocturnal and burrowing mammals are able to avoid extreme temperatures. Diverse opportunistic invertebrates and reptiles occur, along with small numbers of large-ranging ungulates.