Wednesday, 9 February 2011

Mexican Mole Lizard: Strange Lizard-Worm-Snake Like Creature

Mexican mole lizard (Bipes biporus) resting on the groundKingdom: Animalia
Phylum: Chordata
Class: Reptilia
Order: Squamata
Family: Bipedidae
Genus: Bipes
Species: Bipes biporus
Conservation Status: Least Concern (Not threatened)
Common Name(s): Mexican mole lizard, five-toed worm lizard, Ajolote

Today's post is about one of my favorite strange animals, the Mexican mole lizard. As you can see on the image above, the mexican mole lizard looks like a crazy scientist somehow combined a lizard, an earthworm and a snake.

The Mexican mole lizard belongs to the Amphisbaenia suborder, a group of usually legless reptiles, comprised of over 180 extant species.

These little critters occur exclusively in the Baja California peninsula of Mexico, with their habitat ranging from extreme southwestern Baja California State through western Baja California Sur, to the Isthmus of La Paz and the western Cape Region.

Adults have a pink or orange-pink coloration, are 17-25 cm (~7-9 in) snout-to-vent long and have a width of 6-7 mm (~0.24–0.28 in). Some individuals have a somewhat whitish belly. Their skin is closely segmented, giving them a corrugated, worm-like appearance. Their head is blunt.

Similar to earthworms, their underground movement is performed by means of peristalsis (symmetrical contraction) of the segments. They have strong and paddle-like forelegs, with five small but well-developed claws on each limb. Over the course of time, their hind legs have greatly disappeared and are only visible via X-rays as vestigial structures.They are slow and clumsy animals, sometimes swinging around their front legs in an overhand swimming type of motion. The forelimbs are sometimes used to assist in locomotion

The animal's tail is hard to distinguish from the rest of the body and it starts from the vent, which is a small slit-like opening on the underside of the body. The tail makes approximately 1/10 of their total body length, with an average size of 2 centimeters (~0.8 in.). Like lizards, the mexican mole lizard has the ability to discard its tail to escape a predator's grasp or to distract the predator and thereby allow escape. This is achieved by squeezing certain muscle groups around a weak spot in their tail bone, resulting in the tail being "cut off". Although the wound starts to heal almost immediately, contrary to real lizards it doesn't regenerate.

The Ajolote exhibits no external sexual dimorphism which means that individuals look pretty much the same, regardless of their sex.

They can live to be at least two years old.

Mexican Mole Lizard Behavior 
Ajolots are fossorial animals, spending most of their lives below the surface, only coming out of the surface at night, after a heavy rain or to hunt.

They usually move to shallower tunnels during the morning and go in deeper tunnels as the temperature start to get higher. They prefer sandy soils around the roots of certain shrubs which are called mesquites, lurking inside tunnels which are typically less than than an inch (2.54 cm) deep, although tunnels of up to 15 cm (~6 in.) have been reported.

Sometimes, they can also be found under rocks, piles of leaves, and other hiding spots. When noticing something that might be a threat (e.g. a human) they usually react instantly by moving into a nearby tunnel.

Photo of a Mexican mole lizard  (Bipes biporus)
A mexican mole lizard

The Ajolote is an opportunist carnivore and generalist predator, with its diet consisting of:
  • Termites
  • Ants
  • Ground dwelling insects and insect larvae
  • Earthworms
  • Other small animals, like lizards. 

Ants and termites are the most common prey items.

If the prey is above the ground, they usually pull it down below the surface first, before consuming it.

Documentary about the Mexican Mole Lizard

Mexican mole lizards are oviparous (egg-laying) animals, breeding underground and laying one to four eggs during July. The eggs require about two months to hatch, with hatching occurring during the rainy season when food supply is in optimal levels.

Conservation Status & Threats & Protection Measures
The species is listed by the IUCN as of Least Concern and probably has a bright future as it seemingly has few and minor threats. In certain places, the expanding intensive agriculture may have a small negative impact. Furthermore, some individuals are killed when encountered because of misidentification as snakes. However, they spend most of their life underground and this rarely occurs.

Pet trade may also be a problem, however this is believed to have a minimal -if any- impact on their populations.

Part of the species distribution falls under the large Vizca√É­no Biosphere Reserve, and some other protected areas. Furthermore, the mexican mole lizard is protected by national legislation, with the NOM (2003) listing the species under the Pr category (special protection).

Other Bipes Species
The Bipes genus contains 3 more species, which:
  • Bipes alvarezi 
  • Bipes canaliculatus
  • Bipes tridactylus

All four species look pretty much the same and only have minor differences, for example in the number of the digits in their front limbs.
Video showing a Bipes canaliculatus
The mexican mole lizard looks pretty much the same

Other Interesting Facts about the Mexican Mole Lizard
- The mexican mole lizard should not be confused with Ambystoma mexicanum, a species of salamander that sometimes comes by the same common name (ajolote).
- Not much is known about the species natural predators. It is presumed that snakes are one of them, as they are well suited to enter and navigate inside its underground burrow systems.
- Based on a past study that collected 103 adult and 168 juvenile individuals, male and female Bipes biporus juveniles are about equally common. However, the same is not true about adults, with the ratio of females to males being approximately two to one. The causes behind this remain unknown, but could include differential mortality, sampling bias, or perhaps a skewed primary sex ratio.

References & Further Reading
- Dial, B., Gatten, R., & Kamel, S. (1987). Energetics of Concertina Locomotion in Bipes biporus (Reptilia: Amphisbaenia) Copeia, 1987 (2) DOI: 10.2307/1445785
Wever, E., & Gans, C. (1972). The Ear and Hearing in Bipes biporus Proceedings of the National Academy of Sciences, 69 (9), 2714-2716 DOI: 10.1073/pnas.69.9.2714
Kearney, M. (2003). Diet in the Amphisbaenian Bipes biporus Journal of Herpetology, 37 (2), 404-408 DOI: 10.1670/0022-1511(2003)037[0404:DITABB]2.0.CO;2
- Cope, E.D. 1894. On the Genera and Species of Euchirotidæ. American Naturalist 28: 436-437. (Euchirotes biporus)


  1. i think that thsi would be a great science project for the weirdist living animal EVA!

  2. QUESTION: Where does it live? And can somone post more pics of it?

  3. @^^ as mentoined above it leaves in Baja California, Mexico....cant you read and u cn get more pics from google u idiot

    1. shut up, why you gotta be stupidd!

  4. Found 2 of them here in Merced ca

  5. all of you dumb people, calm yourselves down. Just read this stupid text and don't ask questions. Just shut up and read.
    This is to everyone.