INDONESIA, the largest archipelago in the world to form a single state consists of five main islands and some 30 smaller archipelagoes, totalling about 17,508 islands and islets of which about 6,000 are inhabited. Indonesia’s national territory consists 84% of sea and 16% of land. The Indonesian sea area is four times larger than its land area, which is about 1.9 million sq.km and the sea area is about 7.9 million sq km. The five biggest islands are Kalimantan or two thirds of the island of Borneo (539,450 sq.km); Sumatera (473,606 sq.km); Papua, which forms part of the island of New Guinea (421,952 sq.km), Sulawesi (189,035 sq.km) and Java including Madura (132,035 sq.km).
The greater part of the country falls with in the boundaries of the equatorial rain belt. It has characteristically a tropical climate. Its geographical make up is an archipelago of mostly small island surrounded by sea. However, it allows an active air circulation. As a result, the climate is closely similar to that of prevailing in the equatorial zones above the world’s oceans. Abundant rainfall, high temperatures and humidity are characteristic to the average Indonesian lowland climate. The lowest average temperature is 18 degree Celsius.
Moreover, the proximity of the Asian and Australian Continents brings the Indonesian archipelago well within the Asian characteristic that keeps alternating in accordance with the seasons. The trade and monsoon winds coming from the Indian and Pacific oceans temper the tropical character of the climate
Within the Indonesian archipelago lies one of the most remarkable zoogeographical boundaries in the world, which dates back to the glacial period when the sea level fell worldwide. In that glacial period, Java, Sumatra, and Kalimantan lay on the Sunda self and were joined to each other and to the mainland of Asia, but Papua and the Australian continent at that time lay on the Sahul shelf. This original geographical segregation explains why the typical oriental fauna species found in Java, Sumatra and Kalimantan are completely lacking in Papua. Similarly, the marsupials, which occur in Papua, are not found in the Oriental Region.
The region between these two shelves (Maluku, Sulawesi and the Lesser Sunda Islands) has another type of fauna. The bulk of Oriental fauna does not occur in Sulawesi, although it is only 50 km from Kalimantan across the Makassar strait, and the islands, such as Seram and Halmahera, closest to Papua lack the major part of the latter's fauna.
Indonesia is also known for its ornamental fish species which are now being exported to the United States, Japan, and Germany. These ornamental fish species which are known for their colorful shape and beauty include: the Amphiprion fish, the Dascyllus, the red colored Labridae and the Coris Aygula species found in plenty around the Bali strait.
Doctor fishes or Labroidae dimidiatus are ornamental fishes which behave like doctors, examining their patients or pecking the body of other fishes. The most common species among Indonesia's ornamental fishes are the ThaIassoma lunare. The Chaetotontidae have small beaks, but the Forcipiger longirostris and the Rostratus fish are characteristic for their long snouts. The Heniches acuminatus have very long back-fins exceeding their body length and the Monish idol or Zanclus canescens can have a size of 20 cm.
Indonesia lies within the botanical region of Melanesia, covering the Malay peninsula south of the isthmus of Kra, the Indonesia archipelago the Philippines and the whole of Papua New Guinea and Papua except the Solomon Islands. For the most part the Melanesian region is covered by the luxuriant growt of the
characteristical tropical rainforest vegetation, a type of ever-wet vegetation containing a large number of timber species harboring various kinds of epiphytes, saprophytes and lianas. These characteristic features and the high number of genera and species endemic within this region make the flora of Indonesia completely different from that of neighboring continental Asia and Australia, as weIl as from the flora of other tropical areas in the world. The richness of the Melanesian region of which Indonesia represents the major portion, is reflected in the accommodation of close to 40,000 species of pants, or about 10-12% of the estimated number of plant species in the whole world.
Besides the great number of mountains and hills, there are still many rivers scattered throughout the country . They serve as substantial transportation means in certain islands; the Musi, Batanghari, Indragiri, and Kampar Rivers in Sumatra, the Kapuas, Barito, Mahakam, and Rajang Rivers in Kalimantan; and Memberamo and Digul Rivers in Papua. In Java, rivers are very important for irrigation systems, for instance the Bengawan Solo, Ciliwung and Brantas Rivers.
