The Water Monitor (Varanus salvator) is the second-heaviest lizard in the world after the Komodo Dragon (Varanus komodoensis) – a fearsome looking animal with a muscular body, split tongue and sharp claws. Scanning their surroundings by walking upright, defending themselves with infection causing bites and feeding on carrion, birds, eggs and young crocodiles, this aquatic and arboreal carnivore is one of Borneo’s apex predators. Although the water monitor is a common inhabitant of the island’s riparian zones and rivers, we were fortunate to watch this dragon up-close on several occasions. Note the sheer size of the claws in the photograph below – and compare it to the innocent look of the juvenile above…
The Kinabatangang Nature Lodge is a place of great adventure. Their slogan ‘it’s a jungle out there!’ not only refers to the forest surrounding the lodge, but also to a world where it’s ‘eat and be eaten’. This certainly holds true for the many insects inhabiting this environment and its therefore not surprising that mimicry is one of the many mechanisms deployed, either defensive or aggressive. The wings from this mantis (Mantidae) offered almost perfect concealment with the colour, shape and texture resembling the leaf it was hiding under – waiting for the next victim to pass.
There are around 5,600 species of lizards living on our planet and around 1,500 are gecko’s (infraorder Gekkota). Scientists keep discovering new species that in one way or another have adapted to their unique habitat, however, despite all their differences gecko’s share some common traits as for example the regular shedding of skin, the voluntary dropping of their tails when attacked by a predator and large eyes, with vertically elliptical pupils that lack eyelids. Many gecko’s have clearly dilated digits with adhesive toe pads – enabling them to run up smooth and vertical surfaces – while others have slender toes as this Borneo Bow-Fingered Gecko (Cyrtodactylus malayanus) we spotted on a night walk in the Sepilok Forest Reserve.
A common or four-lined tree frog (Polypedatus leucomystax) found in the understory near the Kinabatangang Nature Lodge, Sabah, while spotlighting for the Western Tarsier – another species fond of clinging to trees.
The enormous amount of plant and animal material on the forest floor is decomposed by fungi and bacteria in what is called saprotrophic nutrition – a process in which decaying matter is absorbed and metabolised on a molecular scale. The bigger bits are left for other recyclers such as worms, flies and millepedes, a group of animals often referred to as detritivores. Especially the millepedes are fascinating, roaming through the delicious rotting matter in search for food. Heavily armoured with dorsal plates, equipped with chemical-secreting glands and able to curl themselves into a tight pinball-like ball, these millepedes are able to bulldoze along relatively undisturbed. We thought that the orange-coloured giant Pill Millepede (Glomeridae) and the Tractor Millepede (Polydesmidae) we encountered in Danum Valley were particularly impressive!
Fallen leaves, fruits, branches and trees play a crucial role in the ecosystem of the tropical rainforest – they provide the essential nutrients for the typically poor soil and therefore enable new plant growth. Fungi and bacteria act as decomposers of the litter, breaking up the material into smaller pieces for detritivores such as worms, mites and millipedes. The shapes and colours of the fungi are truly amazing: some look like mushrooms while others resemble corals, tongues or sponges, and with their sometimes bright colours they add a certain magic to this already wonderful world.
Although only covering around 2% of the Earth’s surface, tropical rainforests are home to more than half of all life forms on our planet. Its biodiversity is truly immense, but the answer on why so many different taxonomic groups have evolved in this biome is rather complex. When thinking about the biodiversity of the Bornean forests the name of Alfred Russel Wallace automatically comes into my mind. As collaborator of Charles Darwin and co-author of the famous 1858 paper On the Tendency of Species to form Varieties; and on the perpetuation of Varieties and Species by Natural Means of Selection Wallace is one of the founding fathers of the evolution theory – but where Darwin’s fame got firmly cemented by his book On the Origin of Species, Wallace’s contribution to what is now known as ‘Darwinism’ became almost forgotten. However, with his skills as an animal collector, storyteller and founder of biogeography, Wallace has left behind his own legacy; especially his observation that the islands of the Malayan Archipelago represented a frontier between two faunal provinces (the Indo-Malayan to the west …