June 2021

He who speaks with forked tongue

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He who speaks with forked tongue

We first saw this rock monitor lizard on the ground before it climbed up this tree, then down again, in its effort to hide from us. We get two species of monitor lizards here – the Nile/water monitor (Varanus niloticus) which is Africa's largest lizard, and this slightly shorter stockier rock/tree monitor (Varanus albigularis).

In this photo you can see its distinctive forked tongue. What is absolutely fascinating is that the twin ends of the tongue collect odour particles from the air and then deliver them to the corresponding receptors of the Jacobson's organ (a fluid-filled bi-lobed sensory organ in the roof of the mouth), which can detect differences in strength on each tongue tip, and from this work out the direction of the scent, allowing the rock monitor to follow the scent trail and locate the prey. How clever is that?

They are carnivores and will eat anything from eggs to insects, reptiles, frogs, small mammals, birds and carrion. Rock monitors are found further from water, normally sunning themselves on a rock or in a tree. They can be quite intimidating when disturbed – hissing and swishing their tails, or in extreme cases shamming death.

Both species will defend themselves if necessary by biting, scratching and lashing with their powerful tails, so it’s best to stay on the right side of these intelligent and impressive lizards.

Jenny Hishin
By Jenny Hishin
Author / Guest Guide