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May 16, 2001
"Wallace's Line"
  Real Audio

We have spent today traveling westwards back towards an area where the crew found whales two weeks ago. The coast is impressive with high volcanoes as perfect as Mount Fuji strung along it and reaching dizzying heights. It has been glassy calm, making it possible to see clearly the dolphins of three species that visited Odyssey today. Towards the end of the afternoon, we had a long look at a Sailfish which stayed at the surface and held its ground as Odyssey approached, erecting its enormous dorsal fin and turning its body sideways to us in an obvious threat to ward us off should we be planning a closer approach. But kept coming and it furled its fin and dived, showing us at the last second the most vivid blue body colorations. I have several times seen sailfish, but never before seen one that fully unfurled its impressive dorsal sail.

Papua New Guinea and the region that surrounds it is so astonishingly different from what I am used to that I have been reading avidly in Odyssey's library all day, trying to find out more about the region's plants and animals. I find that this is a region whose natural history sets records. For example, New Guinea boasts the only known poisonous bird, the pitohui, which contains enough homobatrachotoxin to kill any small predator that makes the mistake of eating it. It is also home to the largest bat, the Bismark flying fox. Thailand has the world's smallest bat, called Kitti's hog-nosed bat. And Komodo island boasts the world's largest lizard, the komodo dragon which can grow to weigh 150 kilos and be three meters long. New Guinea has the longest lizard, the 4.75 meter Salvadori monitor. The region also shares with Australia the worlds largest and meanest crocodile, the salt water crocodile (500kg, and 4.5 meters long). And at 6.25 meters the region's reticulated Python is the world's longest snake. The world's longest insect also lives here, all 33cm (that's 13+ inches) of it: the Indonesian giant stick insect. And here, as well, is the world's largest flower, the rafflesia whose blooms can be 91cm in diameter.

Nor do such records stop with the plants and animals. For example, the north coast of Papua New Guinea is surrounded by island arcs and countries more liable to earthquakes than any others, and therefore the North coast experiences more sunamis than any other coastline on earth. The region boasts around 200-300 volcanoes 150 of which are active, and about 16 presently active. This is the most active area of the Pacific Ring of fire. The land is moving about on the backs of the underlying tectonic plates, and whenever these plates collide the plants and animals that are riding on them get to mix. The more dominant and successful ones out compete the others and extinctions take place. There is one place, however where the islands did not collide with the mainland for millions of years, though they came very close. Instead, they remained isolated by deep water channels that prevented the collision of the lands on either side and therefore prevented the mixing of the faunas that lived on opposite sides of those deep channels. This is known as Wallace's line after a contemporary of Charles Darwin's, Alfred Russell Wallace, who came up with the theory of Evolution by Natural Selection independently. Wallace's line runs through the deep water between Bali and Lombok, and between Sulawesi and Kalimantan. To the west are mammals like tigers, elephants, monkeys and wild cattle, while to the east are marsupials (pouched mammals) like kangaroos, wombats, Koala Bears, and giant lizards. Even the vegetation is very different: to the west are tropical rainforests, and to the east thornier, drier types of vegetation. The theory is that the Eutherian mammals (mammals like us and the mammals most of us think of when we hear the word mammal) were more successful than their marsupial ancestors and therefore as they developed and speciated, displaced their marsupial neighbors and advanced as far as they could, until they were stopped by the deeps along Wallace's line. This process ensured that the only marsupials that survived were those left in the refuge that lay to the east of Wallace's line.

It is thrilling to realize that two narrow deep straits were enough to preserve the entire fauna of this region from being overrun by the great explosion of new mammalian forms that took place to the west of those same deeps. So although it will be some weeks before we reach Wallace's line, we are, nevertheless surrounded by the bizarre mammals that were able to survive around here because of that line.

This is Roger Payne talking to you from near Wallace's line in the waters to the north of New Britain.

(c) 2001 Roger Payne

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