Reproductive biology

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 Ram-photyphlops 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 ver-micularis. 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.

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