Small to medium-sized fossorial snakes with smooth, uniformly sized body scales; highly reduced eyes; small, ventrally placed mouth; variably shaped snout; and short tail bearing a sharp terminal spine
2.1–37.4 in (5.3–95 cm)
Number of genera, species
6 genera; 214 species
Endangered: 1 species; Vulnerable: 1 species
Evolution and systematics
The phylogenetic position of Typhlopidae within the order Squamata has been enigmatic and controversial for more than two centuries. Most early taxonomists grouped typhlopids together with various forms of snake-like lizards, such as amphisbaenians, burrowing skinks, and limbless anguids. This practice continued throughout the early nineteenth century until the publication of the sixth volume of Duméril and Bibron's monumental work, "Erpétologie Général ou Histoire Naturelle Complète des Reptiles" in 1844. Based on extensive anatomical comparisons with other squamates, Duméril and Bibron grouped typhlopids together with leptotyphlopids (to the exclusion of superficially similar limbless lizards) into "Scolécophides," one of five major "sections" that they recognized within Serpentes. This classification scheme soon gained widespread acceptance, and the Latinized name Scolecophidia was introduced in 1864 by Edward Drinker Cope.
Most recent workers have at least tentatively accepted the hypothesis that Scolecophidia represents a natural (monophyletic) group. However, this notion has not gone unchallenged. Several morphological and molecular studies have concluded that Scolecophidia may be polyphyletic, including two influential anatomical studies that suggested that Typhlopidae may be placed improperly within Serpentes (i.e., that typhlopids represent a divergent lineage of limbless lizards). Nevertheless, most cladistic analyses of squamate interrelationships have supported the hypothesis of scolecophidian monophyly. Moreover, the majority of such studies have suggested that within Scolecophidia, Typhlopidae is more closely related to Anomalepididae (early blindsnakes) than to Leptotyphlopidae (slender blindsnakes).
The fossil record for Typhlopidae is extremely poor. Only two fossil taxa have been described. Typhlops grivensis is known from three trunk vertebrae found in Middle Miocene deposits in France, and T. cariei is known from seven trunk vertebrae discovered in Subrecent deposits on Mauritius. Given that these species were described solely on the basis of vertebral morphology, their placement in the genus Typhlops must be considered tentative. Unidentified scolecophidian fossils have also been found in Tertiary deposits in Europe, Africa, Australia, and South America, and it is likely that many of these fragmentary fossils represent typhlopid remains. Unfortunately, the very incomplete scolecophidian fossils that have been unearthed thus far have shed little light on the evolution of blindsnakes. However, some of these fossil remains have improved our understanding of the biogeographical history of blindsnakes.
No subfamilies are recognized.
Perhaps the most conspicuous physical characteristic of blindsnakes is their small size. Although Typhlopidae includes a small number of "giant" species that may reach over 2 ft (61 cm) in total length (e.g., Ramphotyphlops proximus, R. unguirostris, Rhinotyphlops acutus, R. schlegelii, Typhlops angolensis, T. lineolatus, and T. punctatus), most species are much smaller, and many reach a maximum adult length of less than 1 ft (31 cm). The smallest blindsnakes known are hatchling Ramphotyphlops braminus, which measure little more than 2 in (5 cm) in length, less than 0.04 in (1 mm) in width, and weigh only 0.005 oz (0.13 g). In contrast, the largest blindsnake, Rhino-typhlops schlegelii, reaches a maximum length of 3.1 ft (95 cm),
a width of almost 1.2 in (3 cm), and a weight of nearly 1.1 lb (0.5 kg).
In general, typhlopids are somewhat stouter than other blindsnakes (Anomalepididae and Leptotyphlopidae). However, "aspect ratios" (total length divided by body width) vary widely within this family, ranging from 16 (in the stocky Brazilian species Typhlops paucisquamus) to at least 130 (in the extremely slender Australian species Ramphotyphlops grypus). In most forms the body is relatively round in cross-section and is nearly uniform in width from the head to the base of the tail. In some larger species, however, the rear part of the body may become markedly distended in adults due to the deposition of fat throughout the posterior portions of the abdominal cavity.
The body scales of typhlopids are smooth, shiny, and strongly overlapping. As in Anomalepididae and Leptotyphlopidae, these scales are more or less circular in shape (at least along their posterior margins) and uniform in size. The only enlarged scales are the anal shields (numbering between one and five) and the scales surrounding the head. The number of longitudinal scale rows encircling the body ranges from 16 to 44, and the number of transverse scale rows along the length of the body ranges from 169 to 709. The body scales are remarkably thick, providing these snakes with an effective line of defense against the bites and stings of the insects on which they feed. This thickening of the epidermis also has a profound effect on ecdysis (shedding of skin). The shed skins of typhlopids (especially those of larger species of Ramphotyphlops, Rhinotyphlops, and Typhlops) are much thicker than those of other snakes and often have a rubbery consistency. In addition, the skin is usually shed in a series of rings rather than in a single piece as in most other snakes.
Like other blindsnakes, typhlopids have small, ventrally placed mouths and highly reduced eyes that are covered by the enlarged scales surrounding the head. However, the general shape of the head is much more variable in Typhlopidae than in Anomalepididae and Leptotyphlopidae. The snout may be bluntly rounded (Cyclotyphlops, most Typhlops, and many Ramphotyphlops), flattened and anteroventrally sloping (Xenotyphlops and some Rhinotyphlops), acutely conical (Acutotyphlops), hooked (e.g., Ramphotyphlops grypus), or trilobulate (Ramphotyphlops bituberculatus) in shape. In most species epidermal glands are visible along the edges of the anterior head scales. In addition, the head shields house numerous tactile organs, and in some taxa (e.g., Xenotyphlops and some Rhinotyphlops) flexible, papilla-like structures project externally from the anterior-most scales surrounding the snout.
The tail is relatively short in most typhlopids, and in many species of Rhinotyphlops and Typhlops, this structure accounts for less than 1% of the snake's total length. However, in some species of Acutotyphlops and Ramphotyphlops the tail is often somewhat longer (5% or more of total length), and in one species that appears to have strong arboreal tendencies (Ramphotyphlops cumingii), the tail may account for as much as 10% of the snake's total length. The tail terminates in a sharp, narrow apical spine in most species, but this feature is absent in some taxa (e.g., Xenotyphlops and the two Asian species of Rhinotyphlops), and in others it may become somewhat enlarged (e.g., Typhlops depressiceps and Acutotyphlops subocularis).
Coloration and patterning are highly variable within Typhlopidae. The majority of species are essentially unpatterned, and most are relatively dark in color (some shade of black, gray, or brown). A wider array of colors and patterns are seen in the genera Rhinotyphlops and Typhlops. Although both of these genera include rather drab, unicolored forms, they also include species boldly patterned with speckles (e.g., R. schlegelii), blotches (e.g., T. congestus), or stripes (e.g., R. unitaeniatus). In such taxa, bright colors (blue, orange, yellow, white) are often incorporated into these elaborate patterns. In most blindsnakes the ventral scales are somewhat lighter in color than the dorsal scales, and in some species (e.g., T. reticulatus) this difference is especially striking. Finally, a small number of typhlopids appear to lack pigmentation entirely (e.g., Xenotyphlops grandidieri).
The most distinctive internal anatomical features of typhlopids relate to their jaw apparatus. In contrast to other snakes, the lower jaw in Typhlopidae is rigid and toothless. The only teeth in the skull are located on the maxillae, which are suspended from the rest of the skull almost entirely by muscles and ligaments. Also peculiar is the orientation of the maxillae, which are positioned horizontally in the mouth. As a result, the transversely oriented maxillary tooth rows point directly posteriorly toward the throat. As in Leptotyphlopidae, the hyoid (tongue skeleton) is Y-shaped and positioned far behind the head. The pelvic apparatus is highly reduced. In most species only the rod-like ischia become ossified, and the pubes and ilia (when present) are generally fused and remain cartilaginous. Femora are absent. In addition to these skeletal characteristics, several unique soft anatomical features have also been documented in Typhlopidae. Perhaps the most noteworthy among these is the solid distal portion of the hemipenis in males of the genus Ramphotyphlops, a feature that is unique among squamates.
Typhlopidae is the largest and most widely distributed of the three families of blindsnakes. It includes six genera and approximately 214 species and has a predominantly tropicopolitan distribution. The genus Acutotyphlops includes four species that are restricted to easternmost Papua New Guinea, the Bismarck Archipelago, and the Solomon Islands. Cyclotyphlops includes a single species, C. deharvengi, which is known only from the type specimen collected in southeastern Sulawesi. The genus Ramphotyphlops contains approximately 57 species that are distributed throughout Southeast Asia, Australia, New Guinea, the Bismarck Archipelago, the Solomon Islands, New Caledonia, and perhaps other Pacific Islands as well. One species (R. exocoeti) is endemic to Christmas Island in the eastern Indian Ocean. In addition, the parthenogenetic flowerpot blindsnake, R. braminus, has been introduced throughout much of the world through the horticultural trade and is now established in Africa, Madagascar, the Seychelles, Mexico, Central America, the Hawaiian Islands, Florida, and even Boston, Massachusetts. The genus Rhinotyphlops includes 30 species, most of which are restricted to mainland Africa. However, R. feae and R. newtoni are endemic to the islands of São Tomé and Príncipe in the Gulf of Guinea; R. simoni is native to Syria, Jordan, and Israel; and R. acutus is endemic to the Indian subcontinent. Typhlops is the largest of the six typhlopid genera, containing approximately 121 species. In the Old World, this genus is distributed from southeastern Europe through Southeast Asia (including Sri Lanka and the Indian subcontinent), and is also found throughout subequatorial Africa, Madagascar, and the Middle East. In addition, a small number of species are known from Príncipe Island in the Gulf of Guinea (T. elegans) and Socotra (T. socotranus), the Comoro Islands, (T. comorensis), and the Andaman Islands (T. andamanesis and T. oatesii) in the Indian Ocean. In the New World, Typhlops is confined to the Neotropical region, ranging from southern Mexico southward to northeastern Argentina. In addition, 26 species are endemic to the islands of the West Indies. Finally, the genus Xenotyphlops includes a single species, X. grandidieri, which is known only from two specimens believed to have been collected in Madagascar.
From a standpoint of species diversity, the worldwide distribution of Typhlopidae is highly uneven; nearly 85% of all recognized species are restricted to the Old World. In addition, approximately 45% of typhlopid species are known only from islands. Typhlopids are known to occur throughout a wide range of elevations, ranging from sea level to at least 7,497 ft (2,285 m) above sea level (T. meszoelyi in the Indian Himalayas).
Blindsnakes occur in a wide variety of habitats, including tropical rainforests, arid deserts, savannas, dry woodlands, cultivated farmlands, and even coastal beaches. They are most commonly found underground (often during the course of digging operations), or beneath stones, logs, or other surface debris (e.g., bark, leaf litter, coconut husks, etc.). They are also frequently discovered in rotting logs, ant hills, and termitaria. Although most typhlopids are believed to be predominantly
fossorial, some forms are occasionally encountered above ground (often following heavy rains), and several species of Ramphotyphlops are commonly found in trees. In fact, one Philippine species (R. cumingii) has frequently been discovered in the root masses of bird's nest ferns (Asplenium nidus) growing near the top of tall forest trees. It is not known whether such species are truly arboreal, or if they only climb trees occasionally in search of food.
The natural behavior of typhlopids is poorly known. Because these small snakes spend most of their lives hidden underground, much of what is known about their behavior derives from observations of the defensive strategies that they implement when they are unearthed by humans. When first exposed, most blindsnakes immediately endeavor to burrow into the soil. If captured, they attempt to escape by frantically thrashing their bodies back and forth, defecating, and voiding the contents of their anal glands. In addition, in many instances the apical tail spine is jabbed forcefully into the captor's skin. No blindsnakes are known to bite in defense, but some will gape widely when restrained, and a small number of Rhinotyphlops and Ramphotyphlops have been reported to emit faint squeaking sounds when handled roughly.
One additional aspect of typhlopid behavior that has been noted with some frequency is the tendency of these snakes to congregate in relatively large groups. This phenomenon, which has also been reported for several leptotyphlopid taxa, has been documented in numerous species of Ramphotyphlops and Typhlops, and may be common among other typhlopids as well. In some instances, more than 20 snakes have been found coiled together beneath a single stone. These congregations do not appear to be related to reproduction, as they usually include both juveniles and adults. Instead, they appear to result from multiple individuals seeking out and utilizing the same favorable microhabitat.
Feeding ecology and diet
Like other scolecophidian snakes, typhlopids feed exclusively on small invertebrate prey. Most taxa feed predominantly on the larvae and pupae of ants, although many species frequently eat termites as well. Several Australian species of Ramphotyphlops are also known to occasionally include earthworms in their diets, and at least one species of Acutotyphlops (A. subocularis) is believed to feed exclusively on earthworms.
Typhlopids feed with astonishing rapidity, in some cases ingesting nearly 100 prey items per minute. They transport their prey using a peculiar feeding mechanism in which the toothed maxillae are rotated in and out of the mouth as many as five times per second. This rapid maxillary raking mechanism allows typhlopids to quickly gorge themselves once they have located an abundant source of food, such as an ant nest or termite mound. Large, heavy-bodied species of Ramphotyphlops, Rhinotyphlops, and Typhlops may consume hundreds of ant larvae and pupae within a single nest before becoming satiated.
Like many other aspects of their natural history, the reproductive biology of blindsnakes is poorly understood. Studies of preserved museum specimens suggest that most typhlopids are oviparous. In the few instances in which clutches of eggs have been deposited in captivity, incubation periods have generally ranged between one and two months. However, the eggs of one African species (Typhlops bibronii) have extraordinarily thin shells and hatch within a week of deposition, and one specimen of T. diardii from Vietnam was found to contain 14 full-term embryos, suggesting that this species may be viviparous throughout at least some parts of its range. The most divergent reproductive strategy among typhlopids is that of Ramphotyphlops braminus, an all-female, triploid species that reproduces parthenogenetically.
Clutch size is highly variable within Typhlopidae. Small individuals of relatively slender species (e.g., Ramphotyphlops braminus, R. wiedii) may deposit only a single egg per clutch. In contrast, clutches of more than 50 eggs have been reported for the "giant" African species Rhinotyphlops schlegelii. Egg size is similarly variable, although precise measurements have been reported only rarely. In the slender species Ramphotyphlops braminus, eggs average approximately 0.16 in (4 mm) in width, 0.59 in (15 mm) in length, and 0.006 oz (0.18 g) in mass. However, in the more heavy-bodied Australian species Ramphotyphlops nigrescens, eggs may be as large as 0.47 in (12 mm) in width, 0.95 in (24 mm) in length, and more than 0.07 oz (2 g) in mass.
Reproduction appears to be highly seasonal in the subtropical species of Typhlopidae that have been studied in detail. In Australian Ramphotyphlops, South African Rhinotyphlops and Typhlops, and a Japanese population of Ramphotyphlops braminus, mating usually occurs in late spring (except in the parthenogenetic R. braminus) and oviposition occurs in the summer. Ramphotyphlops braminus appears to reproduce throughout the year in the Seychelles, suggesting that tropical populations and species may not exhibit such seasonal reproductive cycles.
Mating behavior has been observed only in Typhlops vermicularis. In this species, the male wraps several tight coils around the posterior portion of the female's body during copulation. This behavior presumably allows the male to keep the female's cloaca positioned properly during mating. In some instances, the male and female become intertwined with one another during copulation. On other occasions, the snakes may face in opposite directions while mating.
Only two of the approximately 214 species of blindsnakes are listed by the IUCN. The Mona Island blindsnake (Typhlops monensis) is listed as Endangered, and the Christmas Island blindsnake (Ramphotyphlops exocoeti) is listed as Vulnerable due to its severely limited range. In addition, T. cariei, known only from Subrecent fossil material from Mauritius, is listed as Extinct. However, nearly 20% of the recognized species of blindsnakes are known only from their type localities, and thus the status of many species is uncertain.
Significance to humans
Although some species of Typhlopidae have become incorporated into the legends and folklore of many African and Asian cultures, blindsnakes are of no economic significance to humans.
List of SpeciesSchlegel's blindsnake
Rhinotyphlops schlegelii Bianconi, 1847, Inhambane, Mozambique. Four subspecies are recognized (although some or all of these may represent distinct species).
other common names
English: Schlegel's beaked snake, giant blindsnake; French: Typhlops de Schlegel; German: Afrikanische Blindschlange.
This species ranges between 4.5–37.4 in (11.5–95.0 cm) in total length and between 0.14–1.1 in (3.5–28.1 mm) in midbody diameter. The tail is short, usually 1–2% of total length. Aspect ratios range from less than 20 to more than 50, but average approximately 30. Females grow longer and heavier than males, but have slightly shorter tails. The large rostral scale is strongly angled and heavily keratinized, forming a prominent snout with a sharp, horizontally oriented cutting edge. The eyes are relatively distinct, usually lying beneath the suture between the preocular and ocular scales. There are 30–44 longitudinal scale rows at midbody and 307–624 scales along the dorsal midline. Dorsal color and pattern are highly variable (especially in R. s. mucruso). Blotched, speckled, lineolate, and unicolor morphs are known, exhibiting a relatively wide array of colors (e.g., brown, black, gray, blue, yellow, white). The belly is generally unpatterned and is usually some shade of yellow or white.
Schlegel's blindsnake ranges widely throughout sub-Saharan Africa (Sudan, Ethiopia, Somalia, Kenya, Uganda, Democratic Republic of Congo, Angola, Zambia, Malawi, Tanzania, Mozambique, Zimbabwe, Botswana, Namibia, Republic of South Africa, Swaziland).
This blindsnake inhabits mainly wooded savannas. It is usually found amid soil or underneath stones, logs, and other surface debris.
Schlegel's blindsnake is fossorial. Smaller individuals are frequently seen above ground after heavy rains. Large adults are encountered less frequently, suggesting that they may dig deeper underground than juveniles.
feeding ecology and diet
This blindsnake feeds mainly on the larvae and pupae of ants, although termites are also frequently eaten.
Mating and oviposition apparently occur most frequently in late spring and early summer, respectively. However, this species may breed throughout the year in at least some areas of its range. Clutch size ranges from fewer than 10 to more than 50 eggs, each of which may be as large as 0.47 × 0.83 in (12 × 21 mm). The eggs hatch after a relatively short incubation period of four to six weeks.
Not listed by the IUCN.
significance to humans
Ramphotyphlops nigrescens Gray, 1845, Australia, Paramatta [Parramatta, New South Wales]. No subspecies are recognized.
other common names
English: Eastern blindsnake.
This blindsnake has a total length of 3.8–22.7 in (9.7–57.6 cm). Aspect ratios typically range between 30 and 60. Females grow significantly longer and heavier than males. The snout is bluntly rounded and the eyes are distinctly visible beneath the ocular scales. There are 22 longitudinal scale rows at mid-body. The color is pinkish-brown, purple, or black dorsally, and pink or cream-colored ventrally. The tail often has dark patches on either side of the vent.
Eastern Australia, from southeastern Queensland to Victoria.
The blackish blindsnake occurs in a variety of habitats, from coastal forests to cultivated farmlands. It is relatively common in areas of high human population densities (e.g., Sydney and Brisbane) and is frequently discovered beneath rocks and logs in such areas.
Like other blindsnakes, the blackish blindsnake is fossorial. It frequently congregates in relatively large groups of up to 30
or more individuals. Occasionally, individuals are seen crawling above ground after prolonged drenching rains. One specimen was found 16.4 ft (5 m) above ground in a she-oak (Casuarina).
feeding ecology and diet
The blackish blindsnake feeds almost exclusively on ant brood, although other small invertebrates (e.g., earthworms, leeches) may also be eaten. Ant nests are located by following pheromone trails laid down by adult ants. As many as 1,500 or more ant larvae and pupae may be consumed in a single meal. The species generally feeds only during the spring and summer.
Reproduction in this southern species is highly seasonal. Mating occurs most commonly in late spring, and eggs are deposited during the summer. Clutch size ranges from five to 20 eggs, each weighing 0.04–0.07 oz (1–2 g) and measuring 0.75–1.3 in (19–34 mm) in length and 0.32–0.47 in (8–12 mm) in width. Artificially incubated eggs have taken between 30 and 72 days to hatch (depending on temperature), but natural incubation periods are unknown.
Not listed by the IUCN.
significance to humans
Acutotyphlops subocularis Waite, 1897, Duke of York Island (Bismarck Archipelago). No subspecies are recognized.
other common names
This species has a total length of 7.5–15.5 in (19.1–39.4 cm). The tail is 3.0–4.5% of total length in females, but may be as long as 6.3% of total length in males. Males also have a greater number of subcaudal scales (22–31) than females (14–23). In both sexes, the tail terminates in a relatively large, thornlike apical spine. Aspect ratios range from 23 to 44, but average approximately 32. The snout is somewhat pointed, especially in lateral view (but not as acutely conical as in A. infralabialis and A. kunuaensis). The lower jaw is V-shaped in ventral view. The small eyes are visible beneath the ocular scale. There are 32–36 longitudinal scale rows at midbody, and there are 363–472 middorsal scales. The color is dark brown dorsally, and golden-yellow ventrally.
Bismarck Archipelago (New Britain, New Ireland, Umboi, and Duke of York Islands) and eastern Papua New Guinea (Morobe Province).
Little is known about the behavior of this species. However, numerous morphological features (e.g., pointed head, solidly constructed bony snout, thick neck) suggest that these snakes may be particularly powerful burrowers.
feeding ecology and diet
This is the only species of blindsnake known to feed exclusively (or at least predominantly) on earthworms. Based on the condition of prey found in the stomachs of preserved museum specimens, it appears that worms are swallowed whole.
The reproductive biology is not known, but the closely related A. kunuaensis from Bougainville Island is believed to deposit relatively small clutches (often consisting of only one or two eggs) in August or September.
Not listed by the IUCN.
significance to humans
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Nathan J. Kley, PhD