Northern Cottonmouth vs. Diamondback Watersnake

Both are big, heavy snakes of the southern Illinois bottoms, often seen basking over the water. The Cottonmouth has a broad, blocky head much wider than its neck (a watersnake's head is narrow), a dark band through the eye edged above with a pale line, a vertical pupil and a pit between the eye and the nostril; the Diamondback Watersnake has a plain-sided head with a round pupil, and a dark chain-like net over its brown back that it keeps for life, where an old Cottonmouth is nearly plain black.

Photographs via iNaturalist under Creative Commons licences; the photographers are credited on the sheet.

More comparisons

• Northern Cottonmouth vs. Common Watersnake
• Northern Cottonmouth vs. Plain-bellied Watersnake
• Northern Cottonmouth vs. Mississippi Green Watersnake
• Northern Cottonmouth vs. Eastern Copperhead
• Banded Watersnake vs. Northern Cottonmouth
• Broad-banded Copperhead vs. Northern Cottonmouth
• Brown Watersnake vs. Northern Cottonmouth
• Florida Cottonmouth vs. Northern Cottonmouth
• Florida Green Watersnake vs. Northern Cottonmouth
• Common Watersnake vs. Diamondback Watersnake
• Eastern Copperhead vs. Diamondback Watersnake
• Plain-bellied Watersnake vs. Diamondback Watersnake
• Mississippi Green Watersnake vs. Diamondback Watersnake
• Banded Watersnake vs. Diamondback Watersnake
• Broad-banded Copperhead vs. Diamondback Watersnake
• Glossy Swampsnake vs. Diamondback Watersnake
• Saltmarsh Snake vs. Diamondback Watersnake
• Brazos River Watersnake vs. Diamondback Watersnake
• Concho Watersnake vs. Diamondback Watersnake

Wildsight identifies the reptiles and amphibians of the United States. Every comparison