Mertens' Water Monitor
Varanus mertensi GLAUERT 1951

Mertens' Water Monitor is a member of the subgenera Varanus. With a total length up to 150 cm, this species is one of the smaller members within this subgenera. The greatest members of the monitors are combined in this subgenera.

Mertens' Water Monitor, Varanus mertensi, is very strongly adapted to the life in water, which can be recognize at the strongly depressed, with an clearly seen keel tail, which is approximately 1.5 times as long as SVL. Also the position of the nostrils, positoned on the top of the snout, are a sign, that this goanna prefers to live in the water. The distance between nuchalia and eye is approximately twice as big as the distance between nuchalia and tip of the snout. As soon as the animals dive, the nostrils are automatically blocked by flaps.

The major color of Varanus mertensi is a dark olive green. Some pale yellow spots, surrounded by black scales are irregularly distributed over the back. The throat is bright yellow. An small bluish stripe stretches along the upper jaw, under the ear opening along the neck up to the shoulder belt. The head scales are moderately large, regularly ordered and smooth. 150-190 scale rows are around midbody. The tail scales are slightly keeled, they are not ordered in regular rings since the scales on the underside are larger than the one on top.