Feet & Claws

Monitors use their feet to walk, dig, climb and occasionally tear apart food that is too large to swallow. Species that climb well tend to have flexible toes equipped with long, very thick, sharp, curved claws. The toes permit the claws to swivel and in some larger arboreal species are equipped with a locking mechanism which enables them to support their entire weight with just one of the strong claws if needed. To descend they fall through trees with the claws held back wards, so that they drag through the vegetation and thus slow descent. In this way even very large monitor lizards are able to descend rapidly from the branches of tall trees. The massive claws can provide support both on thin branches and on vertical surfaces (Menens1942, Landsmeer 1981, Auffenberg 1988). In captivity the illustrious tree crocodile can climb vertical surfaces and remain there holding on with its hind feet alone, whilst the front legs reach out for a higher purchase. The front claws can also be used to tear holes in plaster walls and burrow through hard packed substrates. The delightful Australian rock goan nas also have long curved daws and exceptionally long toes enabling them to climb high cliffs and make rapid progress over slippery rocks. Unfortunately there are very few documented observations of these very fast and agile little gems in their natural habitats (Horn & Schurer I 978).

Monitor lizards which spend most of their time on the ground tend to have shorter toes and more slender, straighter claws than those of their climbing relatives (Mertens I 942a). In some species these claws are very long and the front legs are extremely strong and well developed. The Bengal monitor, which is equally at home in trees or on the ground, has longer toes equipped with short, powerful, strongly curved claws. They enable it to be dextrous enough to capture bats roosting in trees yet provide the mechanical strength to break open hardened tennite mounds. A number of monitor lizards (including Gould's goanna and the New Guinea tree monitors) are known to eviscerate larger prey using their foreclaws. The smaller monitors do not have to support such great weights and their claws tend to be much less dramatic. A number of smaller, agile species (such as the rock goannas and the New Guinea tree monitors) have curious groups of scales on the soles of their feet, which are sometimes reported to be sticky to the touch. The pads may be an aid to climbing or they may secrete chemicals of an odoriferous nature (Mitchell 1955; Horn & Schurer 1978; Greene 1976).

Attribution / Courtesy: Daniel Bennett. 1995. A Little Book of Monitor Lizards. Viper Press U.K.