Tortoises cannot swim like turtles can, in fact they would sink and drown if they attempted to enter the water. They are terrestrial creatures. Their shell is made of thick keratin and the tortoise’s body is attached to the inside of the shell. Their shells grow similar to a tree with concentric rings. The dark rings in the shell indicate periods of much growth and we can estimate the years that a tortoise has been alive and growing with these rings. The desert tortoise spends 95% of its life underground – not surprising, considering surface temperatures in its natural habitat can reach 140 degrees Fahrenheit! It can survive a year or more without drinking, as most of its water intake comes from food. When threatened, it will sometimes empty its bladder, rendering it vulnerable to dehydration, so don’t disturb one in the wild unless it’s in immediate danger (e.g., crossing a road). Hatchling mortality is high, but individuals who make it to maturity can expect to live 50 years or much more.
Desert tortoises are an endangered species for many reasons. Most of this is due to habitat loss with more people moving into the desert (Las Vegas, Los Angeles, and other growing cities) and destroying the open habitat that tortoises need to live and breed. Many of the remaining tortoises are being run over or predated on new predators that are attracted by the trash growth in the tortoise’s natural area. The exotic pet trade has also made an impact on their wild population.