The Mexican mole lizard (''Bipes biporus''), also commonly known as the five-toed worm lizard, or simply as '' Bipes'', is a

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

amphisbaenia Amphisbaenia (called amphisbaenians or worm lizards) is a group of typically legless lizards, comprising over 200 extant species. Amphisbaenians are characterized by their long bodies, the reduction or loss of the limbs, and rudimentary eyes. A ...

n in the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Bipedidae Bipedidae is a family of amphisbaenians that includes the extant genus '' Bipes'' represented by three species from Baja California and the southern coast of Mexico and the extinct genus '' Anniealexandria'' represented by one species that lived ...

. The species is

endemic Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...

to the Baja California Peninsula. It is one of three

amphisbaenians Amphisbaenia (called amphisbaenians or worm lizards) is a group of typically legless lizards, comprising over 200 extant species. Amphisbaenians are characterized by their long bodies, the reduction or loss of the limbs, and rudimentary eyes. As ...

that have legs.

Genetic Variation

Studies demonstrate that Mexican mole lizards have very low genetic variation among the three allopatric species found in this genus. All three allopatric species have seven fixed identical loci and only six different fixed loci. This is due to the similar environments that all three species are found in.

Description

''B. biporus'' is pink and worm-like, in snout-to-vent length (SVL) and in width. It lives for one to two years. Its skin is closely segmented to give a corrugated appearance, and like earthworms, its underground movement is by

peristalsis Peristalsis ( , ) is a type of intestinal motility, characterized by symmetry in biology#Radial symmetry, radially symmetrical contraction and relaxation of muscles that propagate in a wave down a tube, in an wikt:anterograde, anterograde dir ...

of the segments. Its blunt head allows it to burrow into sandy soils efficiently. The forelegs are short, strong and paddle-like, while the hind legs have disappeared, leaving behind only vestigial bones visible in

X-ray An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

s. The tail is autotomous without any

regeneration Regeneration may refer to: Science and technology * Regeneration (biology), the ability to recreate lost or damaged cells, tissues, organs and limbs * Regeneration (ecology), the ability of ecosystems to regenerate biomass, using photosynthesis ...

. Due to sacrificing the development of its ear to permit it to dig more efficiently, the Mexican mole lizard has evolved to have its skin transmit vibrations to the

cochlea The cochlea is the part of the inner ear involved in hearing. It is a spiral-shaped cavity in the bony labyrinth, in humans making 2.75 turns around its axis, the modiolus (cochlea), modiolus. A core component of the cochlea is the organ of Cort ...

Reproduction

''B. biporus'' is

oviparous Oviparous animals are animals that reproduce by depositing fertilized zygotes outside the body (i.e., by laying or spawning) in metabolically independent incubation organs known as eggs, which nurture the embryo into moving offsprings kno ...

, and the females lay one to four

eggs An egg is an organic vessel in which an embryo begins to develop. Egg, EGG or eggs may also refer to: Biology * Egg cell, the female reproductive cell (gamete) in oogamous organisms Food * Eggs as food Places * Egg, Austria * Egg, Switzerland ...

in midsummer. The species only breeds underground. The eggs hatch after two months. The juveniles tend to be pink and then turn white as they grow into adulthood. Bipes Biporus don't exhibit sexual dimorphism so their sexual identity is only determined by looking at their gonads.

Geographic range

The Mexican mole lizard (''B. biporus'') is found in the states of

Baja California Baja California, officially the Free and Sovereign State of Baja California, is a state in Mexico. It is the northwesternmost of the 32 federal entities of Mexico. Before becoming a state in 1952, the area was known as the North Territory of B ...

Baja California Sur Baja California Sur, officially the Free and Sovereign State of Baja California Sur, is a state in Mexico. It is the 31st and last state to be admitted, in 1974. It is also the second least populated Mexican state and the ninth-largest state by ...

Guerrero Guerrero, officially the Free and Sovereign State of Guerrero, is one of the 32 states that compose the administrative divisions of Mexico, 32 Federal Entities of Mexico. It is divided into Municipalities of Guerrero, 85 municipalities. The stat ...

and

Chiapas Chiapas, officially the Free and Sovereign State of Chiapas, is one of the states that make up the Political divisions of Mexico, 32 federal entities of Mexico. It comprises Municipalities of Chiapas, 124 municipalities and its capital and large ...

, in

Mexico Mexico, officially the United Mexican States, is a country in North America. It is the northernmost country in Latin America, and borders the United States to the north, and Guatemala and Belize to the southeast; while having maritime boundar ...

. These species tend to be found on this peninsula near the sandy soils in desert with dry shrub land. They spend their time burrowed from 2.5cm to 15 cm.

Behavior

Like all other amphisbaenians, ''B. biporus'' is a

burrowing An eastern chipmunk at the entrance of its burrow A burrow is a hole or tunnel excavated into the ground by an animal to construct a space suitable for habitation or temporary refuge, or as a byproduct of locomotion. Burrows provide a form of s ...

species that only surfaces at night or after heavy rain. It uses its autotomous tail as an escape tactic for predators. Losing a part of the tail while burrowing can plug up the hole behind it, giving it time to escape.

Diet

''B. biporus'' is an opportunist carnivore and eats

ant Ants are Eusociality, eusocial insects of the Family (biology), family Formicidae and, along with the related wasps and bees, belong to the Taxonomy (biology), order Hymenoptera. Ants evolved from Vespoidea, vespoid wasp ancestors in the Cre ...

termite Termites are a group of detritivore, detritophagous Eusociality, eusocial cockroaches which consume a variety of Detritus, decaying plant material, generally in the form of wood, Plant litter, leaf litter, and Humus, soil humus. They are dist ...

s, ground-dwelling

insect Insects (from Latin ') are Hexapoda, hexapod invertebrates of the class (biology), class Insecta. They are the largest group within the arthropod phylum. Insects have a chitinous exoskeleton, a three-part body (Insect morphology#Head, head, ...

s, larvae,

earthworm An earthworm is a soil-dwelling terrestrial invertebrate that belongs to the phylum Annelida. The term is the common name for the largest members of the class (or subclass, depending on the author) Oligochaeta. In classical systems, they we ...

s, and small animals including

lizard Lizard is the common name used for all Squamata, squamate reptiles other than snakes (and to a lesser extent amphisbaenians), encompassing over 7,000 species, ranging across all continents except Antarctica, as well as most Island#Oceanic isla ...

s. It usually pulls its prey underground to start its meal. The species is a generalist predator that feeds on easily accessible prey found in soil, debris, and dirt. Stomach content analyses showed that most prey items were soft-bodied and bore tooth marks, indicating that the lizard bit and chewed them rather than swallowing them whole. Prey items are generally smaller in diameter than the gape of the individual ''B. biporus'' that consumed them.

Predators

Human activity poses a significant threat to this species, alongside its natural predators, as is common among many species. Urban development and agricultural practices often result in

habitat destruction Habitat destruction (also termed habitat loss or habitat reduction) occurs when a natural habitat is no longer able to support its native species. The organisms once living there have either moved elsewhere, or are dead, leading to a decrease ...

, particularly concerning as these creatures typically burrow at shallow depths. Among their natural predators, snakes pose a notable threat, particularly if they are larger in size and share the same habitat. Avise, J C, et al. “Genetic Relationships and Genetic Variation in the Amphisbaenian Genus Bipes.” ''Copeia'', vol. 1976, no. 1, 12 Mar. 1976, pp. 120–120, https://doi.org/10.2307/1443782.

References

External links

ADW: ''Bipes biporus'': Classification

{{DEFAULTSORT:Mole lizard, Mexican

Mexican mole lizard The Mexican mole lizard (''Bipes biporus''), also Common name, commonly known as the five-toed worm lizard, or simply as ''Bipes (lizard), Bipes'', is a species of amphisbaenian in the Family (biology), family Bipedidae. The species is Endemism, end ...

Animals with only two limbs Reptiles of Mexico Fauna of the Baja California Peninsula