The largest lizard in the world, a member of the monitor lizard family, is called Varanus komodoensis by scientists and is known popularly as the Komodo dragon. It is fearsome both in form and in temperament and gets its popular name from its resemblance to our notions of a dragon's appearance. There are 52 species of monitor lizards, ranging from tiny creatures a few centimetres long to the giant Komodo dragon. The Komodo dragons live on four south-eastern Indonesian islands in the Lesser Sunda region: Flores, Gili Motang, Komodo and Rinca. The habitat is hot, seasonally arid grasslands, savannas and monsoon forests.
How big is the Komodo dragon? The largest recorded specimen was 3.13 metres long and weighed 166 kg, but this weight may have included a lot of undigested food. Males commonly grow up to 2.75 metres (nine feet) long and females grow up to 2.3 metres long. The lizards have a long tail and a sprawling four-legged posture, with powerful forelimbs for locomotion. They are active lizards and may be very hostile, lashing out powerfully and accurately with their tails upon the slightest provocation.
The primary prey for adult Komodo dragons is the Sunda deer. The Komodos also eat birds, snakes, fish, crabs, snails, small mammals, pigs, water buffalo, wild horses, younger Komodos and carrion. They will also attack humans and are not averse to snatching a child from a native settlement if the opportunity presents itself.
The primary food detector used by the Komodo dragon is its sense of smell. It has a long yellow forked tongue with which it samples the air, presenting the sample to an organ in the roof of the mouth called Jacobson's Organ, where chemical analysers smell the food by recognising airborne molecules emanating from it.
The basic strategy used by the Komodo dragons in making a kill is to smash the quarry to the ground and to tear it to pieces. The lizard has powerful claws, but its teeth are its most dangerous weapon. These are large, curved and serrated and tear flesh with great efficiency.
The tooth serrations harbour bits of food from the dragon's last meal and large numbers of bacteria grow on these food residues. Some of these bacteria are highly septic which means that a wound inflicted on a prey by a Komodo bite automatically becomes badly infected. If a deer manages to escape an attack from a Komodo dragon it will die within a week from infection and then be eaten by that or by other Komodos. Curiously, the Komodo bite is not deadly to another Komodo who appear to be unaffected by these otherwise deadly bacteria.
The Komodo's jaws and throat allow it to swallow large chunks of meat with great efficiency. A 50 kg female was once observed to consume a 31 kg boar in 17 minutes. The Komodo stomach expands easily and allows an adult to consume up to 80 per cent of its own body weight in a single meal.
Large carnivores such as lions leave about 30 per cent of their kill unconsumed - they do not eat intestine, skeleton, hide or hooves. Komodos leave only about 12 per cent of their prey unconsumed. They eat bones, hooves and hide. Before eating the intestine they removes faeces by vigorously shaking the intestine.
It is estimated that less than 3,500 Komodo dragons live in Komodo Island National Park and the future of the species is at risk. One of the major challenges facing the future of the Komodo dragon stems from the poaching of their primary prey, the Sunda deer. The habitat of the Komodo dragon is also constricting due to encroachment by settlers who slash and burn the monsoon forest. Measures are now being taken to protect the Komodo Dragon.
A good article on the Komodo Dragon was published by Claudio Ciofi in Scientific American, March, 1999.
(William Reville is a senior Lecturer in biochemistry and Director of Microscopy at UCC.)