As much as 19 percent of the world's reptiles are at risk of extinction.

New research at the Zoological Society at London finds that the lizards, turtles and snakes of the world are threatened.

The study focuses on a random sample of 1,500 of the reptile species around the world. This is only a part of the 9,500 known species of reptiles, but serves as a sample for the whole.

"It's essentially an election poll setup — using this sample to give an example of how reptiles are doing as a whole," Dr. Monika Bohm told BBC Nature. "The risk is — if you lose a really important food source you can change food webs quite dramatically."

Reptile vulnerability could be a sign of environmental problems. The animals are very specialized and able to live in a variety of climates and locations, but don't let that fool you. "Reptiles are often associated with extreme habitats and tough environmental conditions, so it is easy to assume that they will be fine in our changing world," said Bohm. "However, many species are very highly specialized in terms of habitat use and the climatic conditions they require for day to day functioning. This makes them particularly sensitive to environmental changes."

Reptiles in tropical climates are the most threatened, due to pressures from logging and agriculture. The study suggests that 50 percent of freshwater turtles are at risk, with 30 percent of all freshwater reptiles at risk. Turtles are in danger because of their use by humans.

"With turtles, what's quite often the case is they are affected by harvesting and they're quite often used for food or the pet trade," said Bohm.

The study, done in conjunction with the International Union for the Conservation of Nature's Species Survival Commission, was published in the journal Biological Conservation. "This gives us an indication of how reptiles are faring and we can compare this to other species groups," said Bohm.