Reptiles
Western Worm Snake
Carphophis vermis · also called western worm snakes
Turning over a flat rock after a heavy rain reveals a small, glossy, dark snake barely as thick as a pencil, its pale pink belly a surprising contrast to its darker back, an animal so committed to life underground that it has little practical use left for eyesight at all.
Overview
The western worm snake, Carphophis vermis, is a small, burrowing snake native to forest and grassland habitat with loose, workable soil across the central United States. Its greatly reduced eyes, near-total underground lifestyle, and distinctive pink belly make it one of the more physically specialised and rarely observed small snakes in its range.
A life that has left eyesight behind
Spending nearly every moment of its life buried in soil, the western worm snake has evolved eyes reduced to little more than light-sensing spots, a trade-off that makes perfect sense for an animal that almost never needs to see anything clearly at all.
Status
Least Concern — widespread and stable across suitable forest and grassland soil habitat throughout the central United States, though rarely observed due to its almost entirely underground lifestyle.
Western Worm Snake: common questions
Why does the western worm snake have such tiny eyes?
This species spends nearly its entire life buried in loose soil, where clear vision offers little practical advantage, so its eyes have become greatly reduced over evolutionary time, functioning more as simple light-sensing spots that help it detect changes between light and dark rather than forming detailed images the way a surface-dwelling snake's eyes would.
Is the western worm snake dangerous to people?
No, this species is completely harmless, rarely growing beyond about 30 centimetres in length and possessing no venom at all, relying entirely on its small size and burrowing lifestyle to avoid predators rather than any capacity to defend itself against a person.
How is the western worm snake different from the eastern worm snake?
The two species are close relatives that replace each other geographically across much of the central and eastern United States, with the western worm snake generally found further west, and while both share a similar burrowing lifestyle and earthworm-heavy diet, subtle differences in colouration and range are typically used to distinguish between them.
Why is the western worm snake rarely seen?
This species spends nearly all of its time burrowing through loose soil and hiding beneath rocks, logs, and leaf litter, only becoming more likely to appear on the surface after heavy rain saturates the soil, meaning even in areas where the snake is genuinely common, direct sightings remain relatively uncommon.