[Killietalk] sumatra

[Robert Goldstein]

SUMATRA
 

Sumatra is a vast, elongate island southwest and parallel to the Malay peninsula, just across the narrow and shallow Strait of Melaka.   Sumatra, Borneo, Java, and surrounding islands rest upon the submerged Asian continental shelf.  The islands and mainland were connected when sea levels were lower during the Pleistocene Era and the shelf was the edge of the sea.  Sumatra is the westernmost island of Indonesia, and second most populous after Java.

 

            To see maps of the shoreline in the past, including the Sunda Shelf upon which much of the land habitat of present day Betta exists, click on http://www.fmnh.org/research_collections/zoology/zoo_sites/seamaps/default.htm.

 

Numerous offshore islands surround Sumatra, including Bangka Island off the southeastern coast, Belitung Island in the Belitung island group just east of Bangka Island, the Riau island group off the middle of the east coast, and the Mentawai islands off the west coast, and Nias Island, the largest of this western group.  

 

The Sunda Strait separates Sumatra from Java to the east. The most important feature of the Strait is Krakatoa volcano, still active and dangerous although most of it is now below sea level.

 

The island is geologically active, with about 100 volcanoes along its southwestern side. Lowlands and brackish swamps lie on the side facing the Melaka Strait. The highest point is Kerinci mountain, at about 10,000 ft/3000 m, but many additional volcanoes and other mountains are almost as high.  The large donut-shaped Lake Toba in the north has its own central island, looking like a royal site surrounded by a moat.  The east side of the island consists of a flat broad lowland and swamp region. The west side is dominated by the mountains, but a narrow band of lowlands between the mountains and the sea also provides Betta habitat. Many significant lakes abound on both sides of and within the mountain range.

 

Betta species are usually located by river systems, provinces, and nearest towns. The provinces, from northwest to southeast, are Aceh, North Sumatra, West Sumatra in the west and Riau in the east, Jambi in the west and Bengkulu in the east, South Sumatra, and Lampung. The principal cities and towns are Medan on the northeast coast, which is connected by ferry to Georgetown (Ayer Itam), an important government center; the small town of Dumai, which is connected by two separate ferry routes to Kuala Lumpur on the peninsula and Melaka farther to the south; Padang in West Sumatra; Palembang in South Sumatra; and Bandar Lampung in Lampung province. Bandar Lampung has a railroad-ferry service to Jakarta, Java to the east, and another ferry that travels much of the length of the island on the Indian Ocean side to Padang.  

   

Sumatra's rivers arise in the mountains and flow down both slopes of the range, a few western streams directly to the sea, but most of the rivers to lowlands.   Based on the Nelles 1:1,500,000 map of Sumatra (Nelles Verlag, Munchen, Germany), the largest rivers are the Alas in the north, the Siak opposite Singapore, the Batang Hari at the mid-point of the island, and the Musi to the south. The map-labeled western slope rivers are, from north to south, the Aceh, Teunom, Woyla, Teripa,  Simpang (Aceh province), Gadis, Batahan (North Sumatra province), many unnamed rivers south through the Lunung Reserve (West Sumatra province),  Airbangis, Pasaman, Masang, Ipuh, Air Seblat, and Semangka (Lampung province), plus about twice as many mapped rivers for which names are not given. All the western slope rivers drain to the Mentawai Strait and the Indian Ocean. 

 

The eastern slope rivers of Lampung province and provinces to the north extend through vast lowlands to the South China Sea or, farther north, the Strait of Melaka or, in the very far north, the Adaman Sea.  The eastern slope rivers are larger and more numerous. They include (from south to north) in Lampung province the Sekampung, Seputih, Terusan, Tulangbawang, and the Mesuji on the border between Lampung and South Sumatra provinces, the Lumpur, Buluranriding, Saleh, Musi, Banyuasin, Calik, and Lalang (South Sumatra province), Hari (including Tembesi, Tabir, Merangin, and Tibo tributaries), Betara, Tungkai (Jambi province), Indragiri, Kampar, Siak, and Rokan (Riau province), Barumun, Bila, Kualu, Asahan, Bah Hapal, Belawan (North Sumatra province), Tamjang, Peureulak, Jamboeye, and Peusangan (Aceh province), again with many more streams not labeled.

 

Species known from Sumatra and adjacent islands include B. imbellis, B. bellica, B. coccina, B. miniopinna, B. chloropharynx,  B. burdigala, B. edithae, B. picta, B. falx, B. fusca, B. tomi, B. renata,  and B. rubra.

 

JAVA
 

The Sunda Strait is east of Sumatra and west of Java. Its most prominent feature is Krakatoa, which remains active and unpredictable. Krakatoa erupted in 1883 with a sound "like artillery" 2,000 miles away in Australia. It could erupt again tomorrow. 

 

A final note. Lake Toba in northern Sumatra fills the caldera of the massive Toba Volcano that erupted some 73,000 years ago in an explosion that dwarfs the 1800s explosion of Krakatoa. Today, Toba's lava flow covers an enormous area and is at places 1000 feet thick.  It's believed that the Toba eruption altered Earth's atmosphere and wiped out all human life except for about 75,000 survivors that became the founder population of all humans alive today, based on DNA analyses of all the principal racial population groups. So although humans date back about a million years, we are all decended from the 75,000 survivors the Toba eruption. (I think I got this right.)


Robert J. Goldstein, Ph.D.
Robert J. Goldstein & Associates, Inc.
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