Urban growth is quickly driving one of the world's most bizarre creatures into extinction. According to a new study, the axolotl (Ambystoma mexicanum), a Mexican amphibian that never metamorphoses past its larval stage, has seen a 90 percent population drop in the last four years. Only an estimated 700 to 1,200 axolotls now remain. The species was already listed as critically endangered on the IUCN Red List of Threatened Species.

The study, led by Luis Zambrano González of the National Autonomous University of Mexico in Mexico City, was published in the August 18 edition of the journal Biological Conservation.

The axolotl exists only in the Xochimilco region of Mexico, in an area just 10 square kilometers in size. The region supplies much of Mexico City's water, and the study found that water quality in the region has declined in the past decade as the metropolis has expanded, putting pressure on the axolotl's sole habitat.

Introduced aquatic species like carp and tilapia have also created competition for the axolotl's food supply. They also eat the amphibian's eggs.

Despite (or perhaps because of) its rarity, the species remains a popular pet, although most breeding for the pet trade is conducted in captivity. Axolotls are also commonly used in scientific research due to their ability to regenerate lost limbs.

By the way, that estimate of 700 to 1,200 axolotls belies the fact that recent surveys on 11 sites in the Xochimilco region "found only a single organism in the whole study region," according to the study's abstract, which suggests "a critical situation for the long-term survival of the axolotl in the wild, and demanding urgent actions toward habitat and population restoration."

Image: Axolotl via Wikipedia