Borneo: An Island of Natural Inspiration

The world's third largest island after Greenland and Papua New Guinea, Borneo remains one of earth's last great natural frontiers, with a wealth of species and habitats that have intrigued explorers and scientists for more than a century.

In prehistory, this vast landmass of rugged mountain ranges and sprawling lowlands was linked to mainland Asia when ice age glaciers locked the waters of the South China Sea to expose the shallow Sunda shelf. The former seabed emerged to form a landscape of forests, floodplains and rivers that allowed successive waves of animals and plants from the continent to colonize Borneo.

When the seas rose again to surround the island, many of the creatures that had invaded Borneo assumed new forms distinct from their cousins elsewhere in the region. Thus, scientists now recognize the island's orang-utan, pygmy elephant and sun bear as endemic subspecies. Other animals, such as the proboscis monkey, bay cat, Bornean bristlehead and the bizarre lungless frog, Barbourula kalimantanensis, have no counterparts anywhere else in the world and are in danger of extinction from human destruction of their habitats for timber and agriculture.

A treasure isle of biodiversity

The island's diverse terrain supports a large variety of ecosystems, including montane forest, limestone vegetation, dipterocarp rainforests, mangroves, fresh water swamp forest and peat swamps. With an estimated 15,000 species, including more than 2,000 orchids, Borneo has more flowering plants than the entire African continent and is a centre of diversity for groups such as palms, pitcher plants, ferns and aroids, the last of which includes the popular aquatic genus, Cryptocoryne.

For fans of exotic wildlife, Borneo's forests and swamps offer a unique chance to spot some of the world's most charismatic land animals and birds. Despite the threat of poachers and plantations, the island is still fairly rich in megafauna such as pygmy elephants, Sumatran rhinoceroses, orang-utans, bantengs, bearded pigs, sun bears and hornbills. Most visitors, however, probably overlook Borneo's immense wealth of reptiles, amphibians and invertebrates. It's a shame, as a few minutes of quiet observation by a trail or jungle stream will likely reveal a bewildering variety of small but colourful beasts.

Aquarists too have much to thank Borneo for. From ancient bonytongues and snakeheads suitable only for the largest tanks to tiny rasboras that glow like living jewels, the island harbours an incredible diversity of freshwater life. More than 400 species of freshwater fish are known from the island, including about 150 endemics. Every year, scientists continue to discover new species such as Rasbora patrickyapi and Paedocypris carbunculus, two recently described cyprinids that occur only in blackwater streams. Many labyrinth fishes, such as delicate chocolate gouramis, spectacular bettas and dazzling little liquorice gouramis, are also endemic to these habitats, which are rapidly disappearing to land clearing for oil palm estates. Asian arowanas, too, depend on these acidic waters for their survival in the wild.

Borneo's wonderful wetlands

The aquatic habitats of Borneo begin at the edge of the sea, where thick mangrove forests guard the shore against damage by erosion and freak waves. Unlike most trees, mangroves are happy to get their feet wet, using stilt-like roots to support their trunks in the soft mud.

In the canopy, the mangroves provide food for proboscis monkeys that eat young leaves and fruit bats that feast on mangrove nectar. The waters below support a complex ecosystem of insects, molluscs and crustaceans that consume fallen leaves and detritus. These invertebrates serve as food for larger crabs and fish, which in turn feed top predators such as crocodiles, herons and otters.

Archerfish, scats, monos, mudskippers, halfbeaks, glassfish and puffers are some mangrove residents that find their way into hobbyist aquariums. In the wild, these fishes can tolerate a wide range of salinities from slightly brackish pools to full strength seawater. But keeping them in tanks can be a challenge as many of these creatures require ample space to roam and are fussy eaters that waste away if denied live food.

Mankind owes much to mangroves, which provide coastal protection as well as nurseries for popular seafood such as tiger prawns and mud crabs. Rich in tannin, mangrove wood is highly valued as a source of charcoal. For aquarists, mangrove roots and branches make ideal driftwood pieces as the dense wood readily sinks in water.

Further inland, Borneo is pierced by many rivers and lakes that form the source of rich freshwater swamp forests. Unlike terrestrial rainforests, many trees in this habitat, such as pandans, are able to withstand periods of submersion in fresh water, using aerial roots or buttressed trunks to obtain air and physical support.

The fruit of these trees sustain numerous creatures, from monkeys and orang-utans to hornbills, large cyprinids and catfish that may serve as important seed dispersers. Crocodiles and false gharials were once common in these swamps and rivers but have now been hunted to extinction in many parts of the island. Smaller predators such as the giant snakehead and the 2 m-long tapah catfish still survive, feeding on schooling species such as barbs and rasboras. Stagnant pools with low oxygen levels support hardier fishes such as swamp eels, walking catfish, gouramis and climbing perches, while loaches, gobies and spiny eels hide in the dense leaf litter.

Once covering nearly 11% of the island's lowlands, Borneo's peat swamps are thought to be among the richest in the region. Unlike freshwater swamp forests, which are fed by adjacent rivers, peat swamps form in coastal areas where the remains of ancient mangroves create thick layers of peat soil. The highly acidic (pH below 4) waters support specialized fauna and flora adapted to thriving in these nutrient-poor conditions. Rich tannins in the peat infuse the water with a dark tea colour that characterizes the swamps' blackwater streams and pools. Among Borneo's habitats, peat swamps are the most vulnerable to uncontrolled burning of forests for commercial plantations and forestry.

In the highlands, Borneo's montane streams are home to probably the richest diversity of hillstream suckers or Balitorids. With flattened bodies and broad pectoral fins that help their bodies cling to rocks, these little fishes feed on aufwuchs in fast-flowing, oxygen-rich streams and require similar conditions to survive in captivity.

Despite the widespread encroachment of man, Borneo still remains an island shrouded in mystery. Many regions close to the coast have been well-explored, but other, more remote, zones, like the so-called Heart of Borneo, a mountainous region in the centre of the island, are only just beginning to reveal the riches of their biodiversity and natural beauty.

Our Inspirations

It's not hard not to be inspired by this amazing natural diversity to embark on a lifelong exploration of Borneo's varied landscapes. We at BORNEO-Wild likewise turn to the aquatic and terrestrial ecosystems of this living treasure island for fresh ideas and elegant solutions to help recreate tropical habitats in your home. Join us as we unveil the natural history of Borneo and other exotic Southeast Asian islands, both in and out of the water, and work to share stories, tools and techniques that will spur you on a journey of discovery and delight in Borneo's wild wonders.