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Life Cycles and Dispersal : Question 1
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Extinct volcanoes in the Auvergne region of France © Paul Billiet


Read the following information and answer the questions.

On the 27 August, 1883, a small volcanic island called Krakatoa exploded. Krakatoa is found in the Sunda Straits between the islands of Java and Sumatra. The explosion was so violent that it was heard in Australia nearly 2000 kilometres away and it blew nearly 20 cubic kilometres of rock into the atmosphere.

The island of Krakatoa was almost completely destroyed. All that was left was a small peak covered in ashes. All life on the island and for 40 km around was killed. For scientists this cataclysm provided them with an ideal laboratory to study how animals and plants recolonize land. The table below summarizes some of their observations:



August 1883

No sign of life.

May 1884

One species of spider found.


The ground was covered in blue-green algae. 11 species of ferns and 15 species of flowering plants found.


Coconut trees seen for the first time.


263 species of animals found. The island was covered in a dense forest.
47 species of vertebrates found including: 36 species of birds, 3 species of bat, 1 species of rat, 1 species of crocodile, 1 species of python and 5 species of lizard.


(a) In an atlas find a map of Java and Sumatra which shows the Sunda Straits clearly. Trace this map and mark the position of Krakatoa on it. Now draw a circle around Krakatoa 40 km in radius (use the scale on the map that you have traced). This represents the area destroyed by the volcano. Label and colour your map clearly.










(b) How do you think that the spider arrived on the island?





(c) How do you think that the plants arrived?






(d) How do you think that each of the vertebrates arrived on the island? Where do you think they came from?