Their range extends throughout the southern half of the Baja California peninsula, west of the Peninsula Ranges. Grismer, ; Papenfuss, The distribution of Bipes biporus reflects the type of environment it inhabits. The climate is seasonably cool in these areas. Mexican Mole Lizards build intricate burrowing systems that run horizontally right below the surface of the soil.
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Their range extends throughout the southern half of the Baja California peninsula, west of the Peninsula Ranges. Grismer, ; Papenfuss, The distribution of Bipes biporus reflects the type of environment it inhabits. The climate is seasonably cool in these areas. Mexican Mole Lizards build intricate burrowing systems that run horizontally right below the surface of the soil. The systems usually emerge to the surface under rocks or logs. Because Bipes biporus is a burrowing species, data are difficult to collect regarding the depths that they are found, and the average and maximum depths in the soil that they inhabit is unknown.
However, Papenfuss , found B. Bipes biporus can be identified by its small, ossified head, a cylindrical body covered with scales in a pattern of vertical rings annuli , and two preanal pores. Juveniles are mainly pink in color, turning white as they mature. Mexican Mole Lizards do not exhibit sexual dimorphism, so sexual identity can only be determined by looking at the gonads. The species within the family Bipedidae differ from other Amphisbaenians in that they have forelimbs.
All other members of this group are completely legless. The three species of Bipedidae have small, powerful forelimbs that are specialized for burrowing. Bipes biporus is the only member of the family with five clawed digits on each forelimb.
When compared to the other two species in the family, B. All species in the family Bipedidae exhibit tail autotomy, but they are unable to regenerate their tails. There is a positive correlation between tail autotomy and body size.
Since the larger specimens are usually older, it can be inferred that older specimens are more likely to be tailless than younger specimens. This is due to the higher likelihood of older animals coming into contact with a predator at some point in their lives.
In the close relative Bipes canuliculutus , hatchlings less than 1 year of age , juveniles greater than one year of age but not yet sexual mature , and adults can easily be distinguished by a size range: those 90 to mm in length are considered hatchlings, to mm are considered juveniles, and greater than mm are considered adults and sexually mature.
Due to the burrowing lifestyle of B. No studies have been done to determine the type of mating system that Bipes biporus may use. Of the specimens collected in the extensive study done by Papenfuss , the ratio of adults to hatchlings stayed relatively constant throughout the study. This suggests that reproductive success remains somewhat stable from year to year and does not depend on the annual rainfall as previously thought, because the study took place during a time of drought.
Papenfuss also found that, on average, larger females tended to lay more eggs than smaller females. Almost twice the number of female adult and juvenile specimens were collected compared to the number of males, although the difference was not statistically significant.
Whether or not this difference was due to sampling bias or if the primary sex ratio was actually skewed could not be determined. Hollingsworth and Frost, ; Papenfuss, Bipes biporus is an oviparous species. Females lay from 1 to 4 eggs per clutch, with an average of 2 eggs per clutch.
The eggs take roughly 2 months to hatch, but there is no mention in the literature on whether the females guard the eggs or display any type of parental care once the eggs are hatched. The eggs are generally laid at the end of June to the beginning of July and begin hatching in late September. Females reach sexual maturity at about 45 months of age. At 45 months, most females are mm or longer, and this length is considered the start of the adult stage in B.
Once sexually mature, females only reproduce, at most, once every other year. Late sexual maturity, small clutch size, and a biennial breeding interval makes the reproductive potential of this species much lower than in most lizards. No data has been collected regarding the extent, if any, of parental care performed by Bipes biporus. Due to its secretive lifestyle, there has been little research done on the average lifespan of B.
Because females do not reach sexual maturity until roughly 45 months of age and only reproduce every other year, average life expectancy must exceed this point.
A captive specimen, captured as an adult, lived for 3 years and 3 months. Papenfuss, ; Slavens and Slavens, Bipes biporus is unique among the other members of the Bipedidae in that it has an enhanced capacity for thermoregulation.
Because Mexican Mole Lizards are ectotherms, they attain their body temperature from the soil of their environment. Typically, Mexican Mole Lizards spend the cooler morning hours near the surface of the ground, and as the temperature of the surroundings rise throughout the day, they retreat deeper into the soil. The capacity for thermoregulation and inhabiting a reliably warm climate enables year-round activity in Mexican Mole Lizards; they appear to lack a regular period of hibernation.
Papenfuss, In terms of locomotion, B. This motion, used by many elongate burrowing animals, occurs when one part of the body anchors in one spot while the anterior portion extends forward while pushing against the anchored spot. Then the anchored portion moves forward and the body anchors at a different spot.
While this process has been found to be energetically expensive in snakes, Bipes may use it more economically, because they seem to move entirely using aerobic respiration. When constructing and extending the underground tunnels, B.
Dial, et al. In contrast to the middle ear structure of most amphisbaenians, the stapes and cartilaginous extracolumella of Bipes biporus are connected by fibrous tissue to a deep fold on the skin of the neck, apparently making B. This structure is likely most effective at intercepting air-borne sounds.
The importance of this highly specialized structure is not completely understood for this otherwise rather primitive species. However, this unique ear structure may be important for locating prey above the surface.
Wever and Gans, Bipes biporus can be described as an opportunistic carnivore. Mexican Mole Lizards will target a variety of prey including ants, ant eggs and pupae, cockroaches, termites, beetle larvae and other insect larvae, and most other small invertebrates. They are considered generalist predators because they will seize anything of suitable size that they contact.
If they encounter a large number of ants, they will eat enough to fill up their stomachs, while their next meal may be a single adult cockroach.
The one characteristic that remains the same for all prey is the practice of B. As is true of many squamates, their teeth are attached to the sides of the jaws in a pleurodont manner. Kearney, ; Papenfuss, Due to its burrowing lifestyle, B.
Nocturnal mammals, such as badgers and skunks, that often prey on burrowing animals may be unable to find and dig up B. The most likely predators of Mexican Mole Lizards are snakes; snakes are easily able to enter the burrow systems constructed by Bipes. However, all species of Bipes are able to autotomize drop their tails as a defense mechanism; it is thought that the autotomized tail may distract the predator or even block the burrow while the Mole Lizard escapes.
However, Mole Lizards cannot regenerate the lost tail for future encounters with predators. Bipes biporus plays a role in the ecosystem as a predator on terrestrial or burrowing invertebrates.
Mexican Mole Lizards may act as a control on certain pest population by consuming numbers of mites, insects, and their larvae. In turn, B. Due to the large number of insects and other small invertebrates that Bipes biporus feeds on, Mexican Mole Lizards undoubtedly play a role in controlling the populations of their prey. Whether they are ever abundant enough to have a significant economic impact is currently unknown.
Kearney, Bipes biporus does no harm to humans or human economic interests; however, people sometimes kill them due to their intimidating appearance.
Many people believe them to be snakes, so if they are dug up during agricultural activities, they are often unnecessarily killed out of fear. Hollingsworth and Frost, Despite their low reproductive potential, Mexican Mole Lizards are considered a relatively stable species, with no immediate concern of endangerment or extinction. These lizards would seem to have at least some ability to adapt to changing environments.
If the habitat of B. The Mexican Mole Lizard is a secretive species that stays hidden underground most of the time, thus limiting its exposure to predation and negative human interactions. They occur in some protected areas and are considered protected wildlife under Mexican law catagory Pr. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends.
Synapomorphy of the Bilateria. Vegetation is typically sparse, though spectacular blooms may occur following rain. Deserts can be cold or warm and daily temperates typically fluctuate. In dune areas vegetation is also sparse and conditions are dry.
This is because sand does not hold water well so little is available to plants. In dunes near seas and oceans this is compounded by the influence of salt in the air and soil. Salt limits the ability of plants to take up water through their roots. Iteroparous animals must, by definition, survive over multiple seasons or periodic condition changes.
Dial, B. Gatten, S. Copeia , 2 : Grismer, L. Berkeley, California: University of California Press.
The elusive Bipes biporus, Baja’s ‘worm lizard’
Long like a small snake, bright pink like an earthworm, and usually burrowing underground with the help of two tiny front legs, the Bipes biporus is an elusive lizard endemic to the Mexican peninsula of Baja California. Plus a bit more info:. 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.
Mexican mole lizard
The Mexican mole lizard Bipes biporus , commonly known as the five-toed worm lizard , or simply as Bipes , is a species of amphisbaenian ,  which is endemic to the Baja California Peninsula. It is one of four species of amphisbaenians that have legs. It is commonly found in Baja California. Their skin is closely segmented to give a corrugated appearance, and like earthworms, their underground movement is by peristalsis of the segments. Blunt heads allow them to burrow into sandy soils efficiently.