Leptotyphlops dulcisTexas Blind Snake

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Geographic Range

Leptotyphlops dulcis has an extensive range, from the Nearctic region to the Neotropics. In North America, this species extends from the southwest United States to northern Mexico. In the United States, L. dulcis is found in southwestern Kansas, western Oklahoma, central Texas, southern New Mexico, and southeastern Arizona. In Mexico, this species ranges from Chihuahua, Coahuila, and Tamaulipas, to Nuevo Leon, San Luis Potosi, Veracruz, Queretaro, Hidalgo, and Puebla. (Ernst and Ernst, 2003; Smith, et al., 1998)

Habitat

Texas blind snakes can be found in arid grasslands and desert fringes as long as moisture and surface cover, such as rocks and logs, are available. They can be found from sea level to roughly 2100 m. Plant species that are prevalent in preferred habitat include yucca, cacti, and thornbush. It is common to find these snakes in prairie grasslands and oak-juniper woodlands, as well as on canyon bottoms and rocky hillsides. Texas blind snakes have been known to take advantage of water sources and compost piles common in suburban settings. (Ernst and Ernst, 2003)

Texas blind snakes are fossorial. They live in a variety of habitat types, as long there is ample food and loose, moist soil. These snakes have been found in arboreal habitats as well in several cases involving following their ant prey, as well as occasionally being deposited in nests by screech owls. Texas blind snakes sometimes follow earthworm trails, a behavior which is assumed to be linked to its lack of specialized digging modifications prevalent in other fossorial reptiles, as this snake does not eat earthworms. If given a choice, clay-loam soils are preferred over other types. (Ernst and Ernst, 2003; Gehlbach and Baldridge, 1987; Gehlbach, et al., 1971)

  • Range elevation
    0 to 2100 m
    0.00 to 6889.76 ft

Physical Description

Texas blind snakes are small snakes. Length ranges from 10 to 30 cm. They are 4 to 5 mm in diameter, have small, uniform, smooth scales, blunt heads, and reduced eyes. Color varies from reddish brown to pink or gray with most pigment in the seven most dorsal scale rows. There are 14 anterior and midbody rows, 12 rows anterior to the vent, and 10 rows around the tail, with a total of 199 to 255 middorsal scales. They have an undivided anal plate. Leptotyphlops dulcis can be distinguished from Leptotyphlops humilis because it has supraocular scales between the eyes, thus creating a total of three scales between the oculars (one prefrontal and the two supraocular). Leptotyphlops dulcis has no teeth on the maxilla, only on the anterior half of the lower jaw. (Cochran, 1991; Ernst and Ernst, 2003)

There is no apparent sexual dimorphism in Texas blind snakes and dissection of the tail is necessary to determine gender. There are four subspecies, two are found north of Mexico: L. dulcis dulcis and L. dulcis dissectus. (Ernst and Ernst, 2003)

  • Sexual Dimorphism
  • sexes alike
  • Range length
    10 to 30 cm
    3.94 to 11.81 in

Reproduction

Males follow female pheromone trails to find mates. "Mating balls" of blindsnakes are not uncommon, where several males try to copulate with the same female at once. Mating occurs under a rock or in a crevice and the male wraps himself around the female in a corkscrew shape. (Ernst and Ernst, 2003)

Because Texas blind snakes live largely underground, little information is available regarding their reproductive behavior. The mating period occurs from late March to June in Texas. While age at reproduction is not known for females, size has been noted. Females averaging 19.3 to 22.5 cm long have been found gravid. Interestingly, females only possess a right oviduct with well-developed seminal receptacle and a short vaginal pouch. While not much is known regarding the ovarian cycle of these snakes, but females have been found containing developed eggs in early summer, which suggests spring ovulation and late summer oviposition. (Ernst and Ernst, 2003; Goldberg, 2003)

Males possess a single, smooth hemipenis that is not distally forked and the sulcus spermaticus is deeply grooved. Additionally, males have spindle-shaped testes at the front caudal third of the body. The left testis usually has fewer lobes than the right testis, usually four to six lobes. While the testicular cycle has not been determined, it is probably similar to that of Leptotyphlops humilis. (Ernst and Ernst, 2003; Goldberg, 2003)

  • Breeding interval
    Studies performed on their close relative, Leptotyphlops humilis, have suggested that females do not produce eggs annually.
  • Breeding season
    The closely related species, Leptotyphlops humilis, mate in spring to early summer.
  • Range number of offspring
    1 to 6
  • Average number of offspring
    4

Texas blind snakes nest in cracks in the earth, roughly 0.76 meters below the surface in colonies. In these colonies, snakes sit atop the clutches of eggs, including multiple clutches in layers. Eggs are long and narrow (15mm by 4.5mm) and have parchment-like shells. Hatching occurs in the fall, late August to September, with roughly 7 cm pink hatchlings emerging. (Cochran, 1991; Ernst and Ernst, 2003)

  • Parental Investment
  • female parental care
  • pre-fertilization
    • provisioning
    • protecting
      • female
  • pre-hatching/birth
    • protecting
      • female

Lifespan/Longevity

No data on lifespan are available. (Ernst and Ernst, 2003)

Behavior

Texas blind snakes are secretive and difficult to observe because of their fossorial habits. Warmer climates correlate to longer emergence periods ranging from May to October in this species. Very low humidity and high temperatures can trigger aestivation deep underground, where they commonly hibernate during the winter. Texas blind snakes are nocturnal, becoming active on the surface only at night with the exception of occasionally on cool or rainy days. They prefer temperatures between 15.9 and 27.5 degrees Celsius and thermoregulate by lying under warm rocks. Texas blind snakes are slow moving, at about 1.2 to 1.5 meters per minute. They sometimes use their tail to lever themselves forward. (Ernst and Ernst, 2003)

Home Range

There is no information on home range size in Texas blind snakes.

Communication and Perception

Texas blind snakes are not blind. Although their eyesight is greatly reduced, they are able to distinguish changes in light intensity. They communicate both interspecifically, as well as intraspecifically, through the use of attractant and deterrent pheromones. The primary food source for these snakes are ant and termite larvae, which they often find by foraging in colonies of these social insects. Texas blind snakes are known for foraging amidst colonies of army ants (Neiv amyrmex nigrescens). Normally, these ants attack threats, but Texas blind snakes are able to produce cloacal secretions, consisting of glycoproteins with free fatty acids, that act as a deterrent toward the ants and allow them to go unharmed in colonies. Additionally, these snakes are attracted to the pheromones that army ant workers secrete. They are also able to use cloacal secretions as an interspecific signal to deter ophiophagus snakes. Finally, the secretions serve as intraspecific signals as well, in that other blind snakes of both sexes are attracted to them. (Ernst and Ernst, 2003; Gehlbach and Baldridge, 1987; Watkins II, et al., 1969)

Food Habits

Termites and ants make up 54 to 64% of the diet of Texas blind snakes. Other soft-bodied larval and nypmhal arthropods are also consumed opportunistically. They have been shown to eat the eggs of these insects as well. One hypothesis regarding their choice of soft-bodied prey over adult arthropods is that the chitonous bodies of adult ants and the heads of termites could potentially be harmful to the blind snake digestive system, although this has not been confirmed. (Ernst and Ernst, 2003; Punzo, 1974; Smith, et al., 1998)

Through the use of olfaction, these blind snakes are able to detect pheromones in the trails of species such as army ants. Often these snakes will move in a concertina or lateral undulatory motion until they encounter those trails, at which time they perform a combination of touching the external nares to the trail, pausing for up to a minute, and flicking the tongue rapidly. (Ernst and Ernst, 2003; Gehlbach, et al., 1971)

The common form of consuming prey in many snakes, such as king snakes, involves jaw ratcheting mechanisms in which each side of the loosely ligamented upper jaw moves independently (unilaterally) from the other and the pterygoid teeth “walk” over the prey, driving it down the digestive tract. The family Leptotyphlopidae, which includes Texas blind snakes, however, possess a much different mechanism of prey-consumption modes. Rather than employ the maxilla in driving prey down the digestive tract, they incorporate the lower jaw in a process called mandibular raking. In this mechanism, they uses bilaterally synchronous motions of the toothed lower jaw to consume soft-bodied insect prey. Often when they are searching for prey, they begin to sway their head horizontally until the snout contacts a larva or a pupa, upon which the blind snake will position its mouth over the prey, sometimes pinning it to the substrate. The larvae is swallowed up until right behind the head, which is broken off by rubbing it against the substrate. (Kley, 2001; Smith, et al., 1998)

  • Animal Foods
  • insects
  • terrestrial non-insect arthropods

Predation

Eastern screech owls are known predators of Texas blind snakes. In fact, they are involved in an unusual, potentially commensalist relationship, in which live Texas blind snakes have been observed in the nests of screech owls. In a study conducted by Gelbach and Baldridge (1987), these owls brought live blind snakes to their nests. The snakes remained in the nest for days, living in the lower levels of the nest off of soft-bodied nest parasite larvae, until the owlets fledged and the snake was able to escape to the ground. It has been proposed that Texas blind snakes are able to survive the initial capture by the owl as it possesses a unique writhing mechanism that allows it to coil around the beak of the owl and remain relatively unharmed upon arriving back at the nest. (Gehlbach and Baldridge, 1987)

Additionally, although raiding army ant colonies do not appear to prey on Texas blind snakes, they are a danger to blind snakes if they detect it amongst their ranks. The pheromones in Texas blind snake cloacal secretions protect them from attack. These pheromones also appear to repel ophiophagous snakes as well. Predators range from large centipedes, snakes, and birds, to mammals such as moles, armadillos, skunks, and domestic cats. (Ernst and Ernst, 2003; Watkins II, et al., 1969)

  • Anti-predator Adaptations
  • cryptic

Ecosystem Roles

As mentioned in the predation section, a commensal relationship has been proposed between Texas blind snakes and eastern screech owls. In this relationship, the owls experience reduced larval parasite populations in their nests, potentially increasing chick size, and the snakes are not harmed assuming they are able to return to the ground in a reasonable amount of time. (Watkins II, et al., 1969)

Commensal/Parasitic Species

Economic Importance for Humans: Positive

There are no known positive impacts of Texas blind snakes on humans.

Economic Importance for Humans: Negative

There are no known adverse effects of Texas blind snakes.

Conservation Status

Texas blind snakes are sometimes killed on highways or drown in suburban swimming pools. Domestic cats also prey on these snakes. The most severe threats to this species are habitat alteration and the use of pesticides. Texas blind snakes are listed as Threatened and are protected in the state of Kansas. (Ernst and Ernst, 2003)

Contributors

Alexandra Prediger (author), Michigan State University, James Harding (editor), Michigan State University.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

carnivore

an animal that mainly eats meat

chemical

uses smells or other chemicals to communicate

cryptic

having markings, coloration, shapes, or other features that cause an animal to be camouflaged in its natural environment; being difficult to see or otherwise detect.

desert or dunes

in deserts low (less than 30 cm per year) and unpredictable rainfall results in landscapes dominated by plants and animals adapted to aridity. 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.

female parental care

parental care is carried out by females

fertilization

union of egg and spermatozoan

fossorial

Referring to a burrowing life-style or behavior, specialized for digging or burrowing.

heterothermic

having a body temperature that fluctuates with that of the immediate environment; having no mechanism or a poorly developed mechanism for regulating internal body temperature.

hibernation

the state that some animals enter during winter in which normal physiological processes are significantly reduced, thus lowering the animal's energy requirements. The act or condition of passing winter in a torpid or resting state, typically involving the abandonment of homoiothermy in mammals.

insectivore

An animal that eats mainly insects or spiders.

iteroparous

offspring are produced in more than one group (litters, clutches, etc.) and across multiple seasons (or other periods hospitable to reproduction). Iteroparous animals must, by definition, survive over multiple seasons (or periodic condition changes).

native range

the area in which the animal is naturally found, the region in which it is endemic.

nocturnal

active during the night

oviparous

reproduction in which eggs are released by the female; development of offspring occurs outside the mother's body.

pheromones

chemicals released into air or water that are detected by and responded to by other animals of the same species

polygynandrous

the kind of polygamy in which a female pairs with several males, each of which also pairs with several different females.

scrub forest

scrub forests develop in areas that experience dry seasons.

seasonal breeding

breeding is confined to a particular season

sedentary

remains in the same area

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

solitary

lives alone

temperate

that region of the Earth between 23.5 degrees North and 60 degrees North (between the Tropic of Cancer and the Arctic Circle) and between 23.5 degrees South and 60 degrees South (between the Tropic of Capricorn and the Antarctic Circle).

tropical

the region of the earth that surrounds the equator, from 23.5 degrees north to 23.5 degrees south.

tropical savanna and grassland

A terrestrial biome. Savannas are grasslands with scattered individual trees that do not form a closed canopy. Extensive savannas are found in parts of subtropical and tropical Africa and South America, and in Australia.

savanna

A grassland with scattered trees or scattered clumps of trees, a type of community intermediate between grassland and forest. See also Tropical savanna and grassland biome.

temperate grassland

A terrestrial biome found in temperate latitudes (>23.5° N or S latitude). Vegetation is made up mostly of grasses, the height and species diversity of which depend largely on the amount of moisture available. Fire and grazing are important in the long-term maintenance of grasslands.

References

Cochran, P. 1991. An unusual microhabitat for a fossorial snake in the rainforest of Peru. Transactions of the Kansas Academy of Science, 94/(1/2): 77-78.

Ernst, C., E. Ernst. 2003. Snakes of the United States and Canada. Washington and London: Smithsonian Books.

Gehlbach, F., J. Watkins, J. Kroll. 1971. Pheromone-trail following studies of typhlopid, leptotyphlopid, and colubrid snakes. Behaviour, 40/(3/4): 282-294.

Gehlbach, F., R. Baldridge. 1987. Live blind snakes (Leptotyphlops dulcis) in eastern screech owl (Otus asio) nests: a novel commensalism. Oecologia, 71/4: 560-563.

Goldberg, S. 2003. Reproduction in the western thread snake, Leptotyphlops humilis (Serpentes:Leptotyphlopidae), from Arizona. The Journal of Arizona-Nevada Academy of Science, 36/1: 5-7.

Kley, N. 2001. Prey transport mechanisms in blind snakes and the evolution of unilateral feeding systems in snakes. American Zoologist, 41/6: 1321-1337.

Punzo, F. 1974. Comparitive analysis of the feeding habits of two species of Arizona blind snakes, Leptotyphlops h. humilis and Leptotyphlops d. dulcis. Journal of Herpetology, 8/2: 153-156.

Smith, H., F. van Breukelen, D. Auth, D. Chiszar. 1998. A subspeices of the Texas blind snake (Leptotyphlops dulcis) without supraoculars. The Southwestern Naturalist, 43/4: 437-440.

Watkins II, J., F. Gehlbach, J. Kroll. 1969. Attractant-repellent secretions of blind snakes (Leptotyphlops dulcis) and their army ant prey (Neiv amyrmex nigrescens). Ecology, 50/6: 1098-1102.