Rena humilis Baird & Girard, 1853

General Appearance

Rena humilis (also referenced as L. humilis in the original text), like most species in the family Leptotyphlopidae, resembles a long earthworm.

Vestigial Eyes

It lives underground in burrows, and since it has no use for vision, its eyes are mostly vestigial.

Coloration and Body Form

This species, commonly called the western blind snake or western threadsnake, is pink, purple, or silvery-brown, shiny, wormlike, cylindrical, blunt at both ends, and has light-detecting black eyespots.

Burrowing Adaptations

It has a thick skull that allows it to burrow, and a spine at the end of its tail that it uses for leverage.

Size

It is usually less than 30 cm (12 in) in total length including the tail, and as thin as an earthworm.

Fluorescence Trait

This species and other blind snakes are fluorescent under low frequency ultraviolet (black) light.

Head Scale Morphology

On the top of the head, between the ocular scales, R. humilis has only one scale, while L. dulcis has three scales.

Overall Distribution Range

R. humilis is found in the southwestern United States and northern Mexico.

United States Range

In the United States, its range extends from southwestern and Trans-Pecos Texas west through southern and central Arizona, southern Nevada, southwestern Utah, and southern California.

Mexico Range

In Mexico, it can be found in the states of Baja California, Sonora, Sinaloa, Nayarit, Jalisco, Colima, Chihuahua, Durango, Coahuila, Tamaulipas, and San Luis Potosí.

Original Type Locality

Its original type locality is recorded as "Valliecitas, Cal."

Type Locality Restrictions

This type locality was first restricted by Klauber in 1931 to "vicinity of Vallecito, eastern San Diego County, California," then restricted further by Brattstrom in 1953 to "the Upper Sonoran Life Zone of the Vallecito area".

Subterranean Habitat

R. humilis lives underground, sometimes reaching depths of 20 metres (66 ft), and is known to enter ant and termite nests.

General Diet

Its diet consists mostly of insects, their larvae, and their eggs.

Habitat Preferences

It occurs in deserts and scrub where soil is loose enough to burrow.

Foraging Behavior

The western threadsnake often forages inside ant nests, eating ant larvae and termites.

Ant Aggression Suppression

Studies by Bateman et al. (2010) indicate that chemical secretions on its body surface help suppress ant aggression, letting it move through ant colonies without being harmed.