M
Species Profile

Mexican Mole Lizard

Bipes biporus

Two arms. One mission: dig.
reptiles4all/Shutterstock.com

Mexican Mole Lizard Distribution

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Endemic Species
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Mexican Mole Lizard-header

At a Glance

Wild Species
Also Known As Five-toed worm lizard, Five-toed amphisbaenian, Two-legged worm lizard, Two-legged amphisbaenian
Activity Nocturnal+
Weight 0.05 lbs
Status Least Concern
Did You Know?

Not a 'true' lizard in the everyday sense: Bipes biporus is an amphisbaenian (worm lizard) within Squamata, specialized for burrowing.

Scientific Classification

Bipes biporus is a burrowing, limbless-looking squamate (an amphisbaenian) notable for retaining a pair of small but strong forelimbs used for digging. Despite the name, it is not a true lizard in the typical sense but a specialized lineage within Squamata adapted to an underground lifestyle.

Kingdom
Animalia
Phylum
Chordata
Class
Reptilia
Order
Squamata
Family
Bipedidae
Genus
Bipes
Species
biporus

Distinguishing Features

  • Elongate cylindrical body adapted for burrowing
  • Two small forelimbs with claws; no hind limbs
  • Reduced eyes and subterranean habits
  • Often mistaken for a “worm” or “snake,” but is a squamate reptile (amphisbaenian)

Physical Measurements

Length
8 in (7 in – 9 in)
Weight
0 lbs (0 lbs – 0 lbs)
Tail Length
1 in (1 in – 2 in)

Appearance

Primary Colors
Secondary Colors
Skin Type Smooth, shiny, tightly overlapping scales arranged in rings (annuli); head with reinforced, shovel-like cranial shields; loose skin around annuli aiding subterranean movement.
Distinctive Features
  • Amphisbaenian ("worm lizard") body plan: elongate, cylindrical trunk with distinct annular rings.
  • Two strong forelimbs (genus Bipes diagnostic): short, muscular arms with five clawed digits for digging.
  • Adult total length commonly reported about 18-24 cm (e.g., Stebbins, 2003; Grismer, 2002).
  • Head blunt and spade-shaped with thickened skull roofing; adapted for head-first burrowing (Gans, classic amphisbaenian functional morphology literature).
  • Eyes greatly reduced and often appear as small dark spots beneath/within scales; external ear openings absent.
  • Tail short and blunt relative to trunk; tail-base may show swelling in males due to hemipenes.
  • Skin often shows fine transverse creases between annuli; body looks 'segmented' even when uniformly colored.
  • Subterranean lifestyle in Baja California/northwestern Mexico typically results in minimal surface wear patterns (little UV-related patterning).

Sexual Dimorphism

External sexual dimorphism is subtle. Reported series suggest females may average slightly longer-bodied, while males can show a more noticeable tail-base swelling from hemipenes and sometimes more evident precloacal pore development; detailed quantification is limited.

  • Tail base may appear thicker due to hemipenes (subtle external swelling).
  • Precloacal pores may be more evident in some males (where visible).
  • Often slightly longer/heavier-bodied in some sampled populations (reported qualitatively in field series).
  • Tail base typically less swollen externally than males.

Did You Know?

Not a 'true' lizard in the everyday sense: Bipes biporus is an amphisbaenian (worm lizard) within Squamata, specialized for burrowing.

Size: adults are typically ~18-24 cm total length (commonly cited maximum ~24 cm).

Genus-level trademark: unlike most amphisbaenians (which are limbless), Bipes retains a pair of powerful forelimbs with 5 clawed digits for excavation.

The species name biporus refers to its diagnostic pair of precloacal pores ("two pores"), a key trait used in identification.

It can move efficiently forward and backward through tight tunnels-an amphisbaenian hallmark that reduces the need to turn around underground.

Endemic to Mexico: naturally found in northwestern Mexico, especially the Baja California peninsula, where it favors soils it can tunnel through (sandy/loose substrates).

Across the genus Bipes (3 living species), forelimbs are retained but digit number varies-B. biporus is the 'five-fingered' Baja representative in a small, highly distinctive lineage.

Unique Adaptations

  • Reinforced, compact skull (burrowing 'ram'): cranial bones are strongly built to withstand pushing through soil-one of the defining adaptations of amphisbaenians.
  • Reduced eyes and low-light sensory emphasis: eyes are small and adapted to darkness; underground navigation relies heavily on touch/vibration and close-range chemical cues.
  • Ringed body (annuli) for traction: the body is encircled by annular segments that help it anchor and push against tunnel walls during locomotion.
  • Powerful forelimbs retained (genus Bipes): short, muscular forearms with long claws function like miniature spades-an unusual trait among worm lizards.
  • Streamlined, subterranean body plan: a cylindrical body and short tail minimize snagging and allow efficient movement through self-made tunnels.

Interesting Behaviors

  • Head-and-forelimb digging: it uses a reinforced, shovel-like head to wedge into soil while the forelimbs rake and pull substrate aside, creating stable tunnels.
  • Subterranean routine: spends most of its time underground; surface sightings often follow soil disturbance (digging, irrigation) or occur at night/after rains when soil is easier to work.
  • Bidirectional tunnel travel: moves backward nearly as well as forward in narrow burrows, allowing rapid retreat without turning.
  • Opportunistic foraging in burrows: hunts small invertebrates encountered in soil and leaf-litter layers (commonly insects and larvae), using close-range cues rather than long-distance vision.
  • Threat response: when exposed, it may writhe and attempt to burrow immediately; if handled, it can bite and brace with forelimbs to resist extraction.

Cultural Significance

Endemic to the Baja California Peninsula, the Mexican mole lizard is a distinctive burrowing reptile with an elongate, worm-like body and only a pair of stout forelimbs. Its unusual appearance has made it a notable species in regional natural history literature and outreach about Baja California's endemic reptile diversity.

Myths & Legends

"Two-legged snake": rural naming traditions in Baja commonly frame it as a snake that somehow kept (or gained) two arms, repeated in local storytelling when the animal is unearthed in fields or gardens.

The English name "mole lizard" comes from its mole-like burrowing life underground. Local myths about the Mexican mole lizard (Bipes biporus) aren't well documented in common scientific sources, which focus on its natural history.

The Mexican Mole Lizard (Bipes biporus) often appears in Baja stories. Its strange worm like body with front arms puzzles people, so it is used to show how odd local animals can be.

Conservation Status

LC Least Concern

Widespread and abundant in the wild.

Population Unknown

Protected Under

  • Mexico: General Wildlife Law (LGVS) - regulates take, possession, and trade of native wildlife via permits/management authorizations
  • Mexico: Protected areas within the Baja California peninsula may provide incidental habitat protection where the species occurs

Life Cycle

Birth 2 hatchlings

Lifespan

In the Wild
0 years
In Captivity
0 years

Reproduction

Mating System Data Deficient
Social Structure Solitary
Breeding Pattern Seasonal
Fertilization Internal Fertilization
Birth Type Internal_fertilization

Mexican mole lizards are solitary burrowers; mating is presumed seasonal with males locating females underground and copulating via internal fertilization. No stable pair bonds are documented; reproduction is expected to involve brief encounters, with no evidence of cooperative care.

Behavior & Ecology

Social Solitary Group: 1
Activity Nocturnal, Crepuscular
Diet Insectivore Termites (Isoptera)
Seasonal Hibernates

Temperament

Secretive fossorial species; avoids surface exposure except under favorable conditions (Grismer 2002).
Typically non-social and non-territorial aboveground; interactions mainly reproductive (Grismer 2002).
Defensive when handled: may bite and vigorously wriggle to escape restraint (Grismer 2002).
Like many amphisbaenians, spends most time underground; surface activity varies with soil moisture and temperature (Grismer 2002).

Communication

None reported; considered essentially silent in available natural-history accounts Grismer 2002
Chemical signaling via cloacal/skin secretions for mate recognition Inferred from amphisbaenian ecology; see reviews in Gans 1978
Tactile contact during mating and close encounters within burrows Grismer 2002
Substrate-borne vibrations from digging/body movements may convey proximity or disturbance cues Gans 1978

Habitat

Biomes:
Desert Hot
Terrain:
Coastal Plains Valley Sandy Rocky
Elevation: Up to 4921 ft 3 in

Ecological Role

Subterranean mesopredator (soil-invertebrate specialist) in Baja California scrub and related habitats.

Regulates local populations of social insects (notably termites and ants) and other soil invertebrates through predation Contributes indirectly to soil turnover and aeration via intensive burrowing associated with foraging Influences below-ground food webs by linking soil invertebrate biomass to higher trophic levels (as prey for larger predators when encountered)

Diet Details

Main Prey:
Termites Ants Beetles and beetle larvae Insect larvae Earthworms Soft-bodied soil-dwelling arthropods

Human Interaction

Domestication Status

Wild

The Mexican Mole Lizard (Bipes biporus) is fully wild with no history of domestication or long-term captive breeding. Human contact is mostly accidental (digging, farming, construction). Some are collected for science or rare pet trade, but pet care is hard and most traded animals come from the wild; people sometimes kill them by mistake.

Danger Level

Low
  • Minor defensive bite or scratch when handled (typically superficial; not medically significant for most people)
  • Zoonotic risk common to reptiles (e.g., Salmonella) if hygiene is poor
  • Risk to the animal from handling stress and dehydration; welfare concern is often greater than human safety concern

As a Pet

Not Suitable as Pet

Legality: Mexican Mole Lizard (Bipes biporus) is often restricted. Not CITES-listed, but Mexican law usually bans wild export without permits. Laws vary by place; check local rules and proof of legal captive breeding.

Care Level: Expert Only

Purchase Cost: $150 - $600
Lifetime Cost: $1,500 - $5,000

Economic Value

Uses:
Scientific research and museum collections Education/outreach (zoo or academic displays, limited) Limited/illicit pet trade Ecosystem services (soil mixing/aeration as a burrower; indirect value)
Products:
  • research specimens/data (non-commercial scientific value)
  • educational exhibits (non-consumptive use)

Relationships

Related Species 2

Three-toed Worm Lizard Bipes tridactylus Shared Genus
Slender Mole Lizard Bipes canaliculatus Shared Genus

Ecological Equivalents 5

Animals that fill a similar ecological role in their ecosystem

Florida Worm Lizard Rhineura floridana Fossorial amphisbaenian occupying a subterranean, insectivorous niche; convergent traits include reduced vision, specialized burrowing locomotion, and a diet dominated by small soil- and leaf-litter invertebrates.
Iberian Worm Lizard Blanus cinereus An obligate burrower (Amphisbaenia) with comparable ecology: forages underground on insects and larvae and has an annulated body form adapted for moving through soil.
Giant Worm Lizard Amphisbaena alba Large-bodied fossorial amphisbaenian. Plays a similar functional role as a subterranean predator of invertebrates and small vertebrates, and has similar head and body specializations for digging, despite occurring in a different geographic region.
Cape Legless Skink Acontias meleagris Fossorial, cryptozoic squamate with limb reduction and soil-burrowing habits. Occupies a comparable niche as a subterranean invertebrate predator, illustrating convergent evolution outside Amphisbaenia.
Western Shovel-nosed Snake Chionactis occipitalis Sand-burrowing desert squamate that forages at or below the surface for small prey. Overlaps in microhabitat use (loose soils) and predator–prey dynamics, though it is a snake rather than an amphisbaenian.

“A species of lizard that looks like a worm”


Mexican mole lizards are also called five-toed worm lizards. They are odd-looking and fascinating. They are a burrowing reptile species. They spend most of their time in underground burrows. Due to their appearance, they are sometimes mistaken for a snake. This makes some humans fear these harmless critters. There is also an old legend that causes people to be afraid of them. It is said that these lizards would come up through the toilet and attack people. This silly myth is, of course, not at all true. It wouldn’t even be possible for them to get into a toilet in the first place.

5 Incredible Mexican Mole Lizard Facts!

  • Mexican mole lizards burrow into the ground.
  • This species is diurnal rather than nocturnal. This means that they are active in the daytime and sleep during the night.
  • Their reproduction is oviparous, which means they are an egg-laying species.
  • They are ectothermic, or cold-blooded. They rely on their surrounding environment, such as soil, to regulate their body temperature.
  • Their tail is autonomous. It can become detached in response to danger.

Mexican Mole Lizard Scientific Name

The Mexican mole lizard’s scientific name is Bipes biporus. It is also called the five-toed worm lizard. The reason for this name is that it is a type of worm lizard (Amphisbaenia) with five toes on each foot. It is sometimes referred to as just “bipes” also. It is in the Animalia kingdom, the Chordata phylum and the Reptilia class. It is of the Squamata order and belongs to the Bipedidae family. The genus is Bipes. The word “Bipes” means two-footed. It is derived from the Latin word “bi” meaning two and “pes” (ped) which means foot. The scientific name “biporus” also uses the Latin “bi” stem and the word “porus” meaning pore or passage in Latin. The origin of the common name “Mexican mole lizard” is that this lizard burrows like a mole and is native to Mexico.

Bipes canaliculutus and Bipes triductylus are closely related to Bipes biporus. B. canaliculutus is commonly called the four-toed worm lizard and the common name for B. triductylus is the three-toed worm lizard. These are all Amphisbaenia species, which is a group of (usually) legless lizards.

Mexican Mole Lizard Appearance & Behavior

This lizard looks similar to a worm. Its body is segmented and cylindrical. It has a long tail. It has two forelimbs with claws that it uses to dig into the soil. Its head is round and blunt. The colors can vary slightly from pale pink to bright pink. Sometimes the colors can be more gray-toned than pink. The colors are usually very light due to the lack of melanin from living underground. Its weight is typically about three ounces. That weight is equal to half the weight of a billiard ball. The five-toed worm lizard’s size is fairly small. It is between 18 and 24 centimeters long from head to tail. It is only six to seven millimeters in width. Its size in length is about equal to between one-half to three-fifths as tall as a bowling pin. Its width is four times as wide as a strand of spaghetti noodle.

This species has evolved from having a set of back legs to losing those and only presenting forelimbs. The reason for this adaptation is unclear, though it may make it easier to squirm through burrow tunnels.
Mexican mole lizards are diurnal. They are most active in the daytime, although they will emerge from their burrows at night. They are not aggressive and seem to be shy, hiding underground most of the time. To get away from predators, they have the ability to break off part of their tails. The downside to this is that it is not regenerative and cannot grow back. Once it is gone, it will not regrow like some species. The tail can also move separately from the limbs.

Mexican Mole Lizard

The Mexican Mole Lizard lizard in its natural environment.

Mexican Mole Lizard Habitat

The Mexican mole lizard lives on the continents of North America and Central America in the country of Mexico. It is native to the Baja California Peninsula. It can be found in the territories of Baja California, Baja California Sur, Guerrero, and Chiapas. It is a terrestrial species that live in desert, shrubland, and dune habitats. The regions it occupies have tropical, Mediterranean, and arid climates and are Nearctic and Neotropical biogeographical regions. This lizard spends its time burrowed in loose soil at depths between two and a half to 15 centimeters. Because it spends most of its life underground, it is hard to spot one of these lizards in the wild.

Mexican Mole Lizard Predators & Threats

The five-toed worm lizard is a carnivore. It is a very opportunistic hunter. It will eat nearly anything small and pliable enough in its environment. The main diet staple is insects. The lizard will grab its prey with its claws and pull it underground to devour it.

The full range of predators to this animal is not well studied. However, they are preyed upon by serpentine species. Because this species is not often seen, some facts remain unknown.

Luckily, this species does not face many serious threats. Other than natural predators, humans are the only other known danger to Mexican mole lizards. Construction and excavation for agricultural and urban development can cause harm to their ecosystem. They have proven to be quite resilient to this threat, however, simply burrowing deeper away from the hazards. They are also sometimes mistaken for snakes and killed for this reason.

The IUCN (International Union for the Conservation of Nature) Red List classifies this species as least concern due to their generous population and extensive distribution. They are protected under Mexican law and NOM (Normas Oficiales Mexicanas) regulations. NOM is a Mexican organization that regulates trade and exports.

What eats the Mexican Mole Lizard?

Snakes eat the Mexican mole lizard. They often share the same habitat and can easily capture and kill them, especially if they are bigger than the lizards. They are the only known predator to these lizards. Although, they are probably eaten by other animals as well.

What does the Mexican Mole Lizard eat?

The Mexican mole lizard mostly eats ground-dwelling insects and larvae. It will also eat small lizards. Some choice items on the menu for this reptile include earthworms, crickets, ants, termites, and cockroaches as well as the larvae of these insects.

Reproduction, Babies and Lifespan

Not much is known about the mating rituals of this elusive species. There are a few established reproductive facts about these lizards though. They reproduce sexually in the summer around the month of July. They typically only reproduce as often as once in a two-year period. They breed and lay their eggs in the soil underground. The female lays two eggs on average but can lay one to four. It takes about two months for the eggs to hatch.

When the eggs hatch in September, the baby lizards weigh less than one ounce. The hatchlings already know how to burrow and are most likely somewhat independent because of their ability to move around on their own.
The normal lifespan for these lizards is between one and two years. The oldest recorded was a little over three years old and lived in captivity.

Mexican Mole Lizard Population

There is not a specific number estimate for the population, although it is believed to be extremely abundant and stable. There is no threat to the decline of this species. They are of least concern on the IUCN Red List because there is no foreseen danger of extinction any time in the near future.

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Sources

  1. EOL / Accessed October 10, 2021
  2. IUCN Red List / Accessed October 10, 2021
  3. iNaturalist / Accessed October 10, 2021
  4. Ripley's / Accessed October 10, 2021
A-Z Animals Staff

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Mexican Mole Lizard FAQs (Frequently Asked Questions)

Five-toed worm lizards are carnivores.