Reptiles
Queen Snake
Regina septemvittata · also called queen snakes
Most snakes will eat whatever they can catch. The queen snake eats almost nothing but crayfish, and not just any crayfish — it specifically targets ones that have just shed their hard shell, when they are briefly soft and defenseless, a feeding strategy narrow enough to make this snake a living barometer of stream health.
Overview
The queen snake, Regina septemvittata, is a slender, non-venomous water snake of clean, well-oxygenated streams across the eastern and central United States. It hunts almost exclusively freshly moulted, soft-shelled crayfish, basking on overhanging branches and dropping into water at the first sign of danger.
A diet that doubles as a warning system
Because crayfish are themselves sensitive to pollution and sedimentation, a thriving queen snake population is a strong sign of a healthy stream — and a declining one can be an early warning of trouble long before other damage becomes obvious. Females give birth to live young, sometimes more than twenty at once.
Status
Least Concern but decreasing in areas where water quality has degraded, since the species has little ability to adapt when its highly specific crayfish food supply disappears.
Queen Snake: common questions
Why does the queen snake eat only freshly moulted crayfish?
A crayfish that has just shed its old, hard exoskeleton has a soft, still-hardening new shell for a short period afterward, making it considerably easier for a queen snake to seize, subdue, and swallow compared with a fully hard-shelled crayfish, which could injure the snake or simply be too difficult to handle and consume safely. This narrow feeding window has shaped the queen snake into one of the most dietary specialised snakes known, with its entire ecology closely tied to the timing and availability of crayfish moulting.
Why is the queen snake considered a good indicator of water quality?
Because its survival depends so directly on a healthy, abundant crayfish population, and crayfish themselves are quite sensitive to water pollution, sedimentation, and other forms of stream degradation, the presence of a thriving queen snake population is generally a strong sign that the stream ecosystem supporting it is also reasonably healthy. Conversely, a decline or disappearance of queen snakes from a stream where they were previously found can be an early warning sign of deteriorating water quality even before other, more obvious signs of ecological damage appear.
Is the queen snake venomous or dangerous to humans?
No, the queen snake is entirely non-venomous and poses no danger to humans, generally relying on speed and its strong swimming ability to escape into water when threatened rather than attempting to bite. Its highly specialised diet of soft-shelled crayfish also means it has little reason or ability to bite defensively in a way that would cause any meaningful harm to a person, and it is considered a docile species overall.
What happens to queen snake populations if local crayfish decline?
Because the queen snake's diet is so narrowly focused on crayfish, and specifically freshly moulted individuals, a significant decline in local crayfish abundance, whether from pollution, habitat disturbance, or the introduction of competing or predatory species, can directly and severely affect queen snake populations even if the physical stream habitat otherwise still appears largely intact. This tight dietary dependence is exactly why the species is considered particularly vulnerable to certain kinds of environmental change compared with snakes that can simply switch to alternative prey when one food source becomes scarce.