Head to head
Water Snake vs Garter Snake
Across much of the eastern and central United States, the two snakes people meet most often near ponds and streams are water snakes and garter snakes. They are close relatives, both harmless to people, but they differ in build, temperament, and how tied to the water they are.
| Water Snake | Garter Snake | |
|---|---|---|
| Genus | Nerodia | Thamnophis |
| Build | Heavy, thick-bodied | Slender and lightweight |
| Pattern | Crossbands or blotches; darkens with age | Usually three lengthwise stripes |
| Tie to water | Strongly aquatic; stays near water | Generalist; swims but not water-bound |
| Diet | Mostly fish and amphibians | Worms, amphibians, fish, slugs |
| Temperament | Defensive; bites, musks, bleeds freely | Mild; usually just musks |
| Venom | None | Very mild rear-fang; harmless to people |
| Young | Live birth, often 20 to 40 | Live birth, often 10 to 40 |
Water Snake vs Garter Snake: common questions
How do I tell a water snake from a garter snake?
Look at the pattern and the build. A garter snake is slim and marked with stripes that run lengthwise down the body, usually one along the spine and one along each side, on a darker background. A water snake is noticeably thicker and heavier for its length and is marked with dark crossbands at the front of the body or a checkerboard of blotches, never clean lengthwise stripes, and older water snakes can look almost uniformly dark. Behaviour helps: a garter snake found well away from water in a garden or field is doing what garter snakes do, whereas a water snake is almost always in or right beside water and drops in with a splash when disturbed.
Are either of them dangerous?
Not to people. Neither is going to cause a medically serious bite. Water snakes have no venom at all; they defend themselves by biting hard and repeatedly and by releasing a foul musk, and because their saliva contains a mild anticoagulant the many small tooth punctures bleed more than expected, which looks worse than it is. Garter snakes do produce a very mild venom in a rear gland, used to subdue frogs and worms, but they cannot deliver it effectively to a person, and the most that happens is minor local itching or swelling in someone sensitive. Both should simply be left alone, at which point both prefer to flee.
Are water snakes and garter snakes related?
Closely. Both sit in the subfamily Natricinae, the same broad group as the grass snakes of Europe, and they are among each other nearest relatives in North America. They share live birth, a fondness for damp habitats, a diet heavy in cold-blooded prey, and the habit of musking when handled. The main divergence is ecological: the Nerodia water snakes specialised as heavy aquatic ambush hunters of fish and frogs, while the Thamnophis garter snakes stayed slim and generalised and spread into almost every habitat in North America, becoming the most widespread snakes on the continent.