The diamondback water snake (scientific name Nerodia rhombifer) is a common reptile often found near aquatic environments. This snake frequently causes confusion due to its appearance and defensive behaviors, leading many to question if it is dangerous. Understanding the characteristics and habits of the diamondback water snake can help clarify its true nature.
Are Diamondback Water Snakes Venomous?
Diamondback water snakes are not venomous. They are a type of colubrid snake, a large family that includes many non-venomous species. These snakes primarily feed on fish and amphibians, which they overpower rather than envenomate.
Identifying a Diamondback Water Snake
Diamondback water snakes are relatively large, heavy-bodied snakes. Adults typically measure between 30 and 60 inches (76-152 cm) in total length. Their coloration ranges from greenish-brown to dark olive, with a distinctive pattern of dark, diamond-shaped blotches along their backs. These blotches are often connected by alternating dark bars on the sides, forming a net-like appearance.
The underside of a diamondback water snake is usually yellow or lighter brown, marked with dark spots or half-moon shapes. Their scales have prominent ridges, known as keels, giving them a rough texture. The eyes are typically round with black pupils, and their head is relatively flattened. Younger snakes often have more pronounced patterns that may darken as they age.
Distinguishing from Venomous Look-Alikes
Diamondback water snakes are often mistaken for venomous snakes, particularly the cottonmouth (also known as water moccasin), due to shared habitats and some similar appearances. Their head shape differs; cottonmouths have a broad, triangular head with prominent venom glands, while water snakes have a more rounded, less distinct head. When viewed from above, a cottonmouth’s eyes are often obscured by an overhanging scale ridge, giving them a “browed” appearance, whereas a water snake’s round eyes are clearly visible.
The shape of their pupils is another distinguishing feature. Cottonmouths possess vertical, cat-like pupils, while diamondback water snakes have round pupils. Behaviorally, cottonmouths often float with most of their body on the water’s surface, while water snakes typically swim with only their head and a small portion of their back visible. When threatened, a cottonmouth may display the white interior of its mouth, a behavior from which it derives its name, a display not seen in water snakes.
Encountering a Diamondback Water Snake
When a diamondback water snake feels threatened, it exhibits several defensive behaviors. They may flatten their bodies and heads to appear larger and more intimidating. These snakes are known to hiss loudly and strike repeatedly if cornered or handled. They might also bite, and while their bite is not venomous, their sharp teeth can cause painful lacerations that may bleed profusely, as they are adapted for gripping slippery prey like fish.
If a bite occurs, cleaning the wound thoroughly with soap and water is important to prevent infection. These snakes may also release a foul-smelling musk from glands at the base of their tail as a defense mechanism. Maintain a safe distance and avoid attempting to handle or provoke the snake. Diamondback water snakes play a role in their aquatic ecosystems by preying on fish, frogs, and other aquatic creatures, including carrion.