Overview
The Rhombic Night Adder (Causus rhombeatus) is a distinctive, widely distributed venomous snake belonging to the primitive night adder genus Causus within the viper family Viperidae. Ranging broadly across the savannas and wetlands of Sub-Saharan Africa, this terrestrial predator is instantly identified by a prominent, dark V-shaped chevron pointing forward on the top of its head. Despite its common name, it is frequently active during daytime hours, functioning as an agile, dedicated predator of toads and frogs across moist habitats.
Biology and Physical Characteristics
Causus rhombeatus displays a stout, cylindrical body covered in weakly keeled scales that give it a smooth, glossy appearance uncharacteristic of typical rough-scaled vipers. Its dorsal coloration is light gray, olive, or pale brown, boldly patterned with a vertebral series of 20 to 30 dark brown, rhombic blotches edged in crisp white. Its head is barely distinct from the neck, covered with large, symmetrical shield-like scales rather than the small fragmented scales seen in true vipers. It possesses moderately long, semi-hollow fangs in the front of its mouth that fold back when closed, connected to extraordinarily elongated venom glands that extend far back into the body cavity.
Behavior and Ecology
Causus rhombeatus is an obligate anuran specialist whose diet consists almost exclusively of common toads and frogs. When hunting, it relies on keen vision and tongue-flicking olfaction to track amphibians into damp marshes, watercourses, and garden compost piles. When confronted by a predator or human, it inflates its body, flattens its neck in an impressive cobra-like hood, and hisses loudly while lunging forward aggressively. Unlike most viperids which give birth to live young, Causus rhombeatus is oviparous, with females laying clutches of 10 to 25 eggs in warm, decomposing organic vegetation.
Conservation and Human Impact
Evaluated as Least Concern by the IUCN, the Rhombic Night Adder is common and highly adaptable, often flourishing in irrigated gardens, suburban parks, and agricultural lands where artificial ponds support dense toad populations. While its cytotoxic venom causes acute local swelling, pain, and mild tissue necrosis in humans, bites are rarely life-threatening and antivenom is seldom required. It plays a significant ecological role in controlling amphibian population explosions and rodent activity in wet savanna ecosystems.
Interesting Factoid
Despite being called a ‘night adder,’ this snake loves hunting fat toads in broad daylight, and when scared, it puffs up its neck to pretend it’s a terrifying spitting cobra!
Last updated: October 2026