At all levels of the jungle, the fauna seems invisible, but it is there.
Down on the ground, thousands of tiny animals clean the jungle of corpses and vegetable remains.
Their work is often overlooked, but it vital for the system.
The zoological order of insects is the most numerous in the rainforest.
It is also one of the least well-known: thousands of species living here have not yet been discovered or catalogued by man.
Much of the local fauna can be found up in the trees.
These crab-eating macaques are just one of the ten species of macaques that live in the archipelago.
There are 31 species of primates alone, of which 23 are endemic, that is, exclusive to these islands.
Isolation gave rise to many endemic species, and incredible biological diversity.
Here, we can find tropical rainforests, mangrove swamp, and savanna.
Each one has its own particular fauna and flora.
In some cases, the species are exclusive to the archipelago, or may be even be restricted to a single island.
On other occasions, they are varieties which can also be found in Asia or Australia,
the two continents with which the islands of Indonesia came into contact.
This is the case of the second largest bovine in the world, the banteng.
The banteng, weighing 900 kg. and almost 2 metres high, prefers the open spaces to the interior of the jungle.
There, they find pasture, and have greater possibilities of detecting potential enemies.
Their size is only surpassed by one other bovine, the Indian gaur,
which can weigh up to a tonne, and stands some 30 centimetres higher.
Groups of bantengs are composed of a number of females, led by a dominant male,
who constantly watches over his harem.
In the ancient past, they could be found throughout continental south-east Asia.
They were an important source of food for the local population, and are today domesticated on some islands.
The wild banteng, however, has been hunted intensively and now only survives in Burma, Thailand, Borneo, and here, in Java.
Unlike man, few predators would even attempt to fell a prey of this size.
Their main enemy lies hidden in the depths of the jungle, where it is virtually invisible.
It is the largest predator on the island, an animal feared and venerated by man since ancient times
the tiger.
Today the banteng almost never comes in contact with a tiger.
As a result of the intensive hunting they have been subjected to,
the population has shrunk to such an extent that, in Java, they are virtually certain to become extinct.
This same threat hangs over the largest inhabitant of these jungles.
It was precisely on this island, Java, that the first explorers found one of the most mysterious animals of the archipelago.
The natives described it as a being of prehistoric appearance, with a single horn, like that of the legendary unicorn.
The animal lived inside the jungle, which made it difficult to find.
For a while, the only proof of its existence were the local stories,
strange piles of excrement which appeared in different places within the jungle,
and tracks which on occasions were seen on the wet ground, beside vegetation which had clearly been bitten into.
The mysterious animal did, however, eventually surface.
The Javan rhinoceros is one of the rarest mammals on earth.
It is slightly smaller than the Indian rhinoceros, and the female either has a very small horn, or none at all.
This has proven to be a blessing, as they are entirely without value for the poachers.
Despite this, they are in serious danger.
At present, Java has the greatest number, but even here there are only 50 individuals.
The rhinoceros had barely stepped from the pages of legend, when it became in danger of extinction.
The rhinoceros is one of the species which arrived in the archipelago during the glaciations, then found themselves cut off.
With the rise in sea-level, only those animals or plants capable of crossing the water were able to reach the islands.
One of these colonised the muds of the estuaries, at the point where the fresh water of the rivers runs into the sea.
These trees form an impenetrable maze of roots and trunks. An intermediate ecosystem which is neither land nor sea.
Conditions here are not the most ideal: the mud is very acid, has little oxygen, and extreme levels of salt.
But the mangrove has the necessary mechanism to overcome these obstacles: its seeds.
The seeds of the mangrove are not only faced with these problems, but must also struggle against tides and currents.
In order to achieve this, they germinate on the tree itself, and develop a stem up to 40 cm long.
Only then do they break off.
If this liberation coincides with low tide, they will cling to the ground and be able to take root.
From then on, the challenge will be to overcome the lack of oxygen.
The trick is to grow long aerial roots, or create vertical tubes, the pneumatophores, which rise up like small breathing pipes.
This seed has fallen during high tide, but it will not die. Its mission is to float off, in search of new territories to colonise.
Below the mangroves, there lies another universe, a world which since ancient times has fascinated and terrified man.