Wild Life
07.26.2017

Bipes Aren’t Coming for You

A mysterious worm lizard squirms its way out of the Baja sand and straight into our hearts.

To see a Spanish translation of this video, visit bioGraphic’s YouTube channel.

Scanning the desert landscape of Mexico’s Baja Peninsula, few people would imagine what crawls beneath the surface. Bright pink, with rudimentary eyes and just two limbs, Mexican mole lizards (Bipes biporus) look more like giant earthworms than reptiles. And like earthworms, these strange-looking creatures spend the vast majority of their lives burrowing underground. As a result, they go largely unnoticed—and underappreciated for the important role they play in this environment.

Mexican mole lizards are members of a group of nearly 200 mostly limbless, burrowing lizards known as Amphisbaenia. Only this species and two others in the genus Bipes still have small front limbs. Amphisbaenians can be found in many parts of the world, including Central and South America, Africa, southern Europe, and the Middle East. Mexican mole lizards, however, live only in Baja, sandwiched between the Gulf of California and the Pacific Ocean, where they are thought to have been isolated from closely related species on mainland Mexico for some 20 million years.

Mexican mole lizards tunnel through sand, loose soil, and leaf litter with their small but powerful limbs. Their diet consists of a wide variety of prey, from earthworms and insects to arachnids and small lizards—essentially anything they can catch and swallow. While their eyes are greatly reduced compared to most lizards, a massive bone in their middle ear allows the surprisingly fierce predators to detect vibrations in the ground and track their prey. Only rarely do mole lizards surface, either after a rain or under cover of darkness as they search for food. This particular individual was caught (and released) by scientists from the Islands and Seas conservation group, who were using pitfall traps (open buckets buried up to the rim) to sample invertebrates near Baja’s Scorpion Bay.

Although Mexican mole lizards are seldom seen, surveys in the 1970s by scientists from UC Berkeley and the California Academy of Sciences revealed that the species is actually quite abundant throughout Baja. In fact, based on these studies most experts think the species may be the most common reptile in the region. While little is known about the Mexican mole lizard’s life history and behavior, the species’ abundance and the unusual niche it fills as an underground predator suggest that it’s a critical member of the region’s food web.

San Juanico, Baja California Sur, Mexico

Kaitlyn Kraybill-Voth

Kaitlyn Kraybill-Voth is a multimedia journalist and illustrator who believes there is treasure everywhere. She especially wants to give the underrated players in nature their time in the spotlight. Her favorite way to do this is by including elements of beauty, art, and whimsy to her work.

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