The Wallace Line: Why don’t animals cross this mysterious line?

The Wallace Line is an invisible ocean barrier in Indonesia that separates Asian fauna from Australian fauna.

Despite the distance of only 35 kilometers between the islands of Bali and Lombok, this line clearly separates the world of elephants and tigers from the world of kangaroos and kazoos.

The Wallace Line is named after the British naturalist Alfred Russel Wallace.

Why is it being so? Blame it on deep ocean trenches that have existed for millions of years, even during periods of low sea level, preventing species from crossing the line.

What’s surprising is that even fish rarely cross this barrier, as the deep sea separates different ecosystems with unique conditions.

Birds, while capable of long-distance flight, also rarely cross the line, as the conditions on the other side are very different: new predators, competitors, and a lack of familiar food.

These factors, along with evolutionary history, keep birds in familiar habitats.