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Biological Environment > Invertebrates Free From Water |
Earth Earlier Earlier 300 Million Years ago Later Earth After Animals Later |
This site tells the story of the history of the universe. Click Earlier and Later to follow the story. Note: Many facts have been simplified to make them easier to understand. |
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Once the seed plants had evolved ways of reproducing without surface water, there was lots of new food which animals could eat. But first they had to solve exactly the same problem that the plants had just solved: how to reproduce without surface water.
Among the arthropods the insects, spiders and many other groups evolved ways to do it. Reproduction involved the male passing his sperm to the female. Sometimes he passed her a packet containing sperm. Often he injected the sperm into her body. The female used the sperm to fertilize the eggs while they were still in her body. Then she covered the eggs with a hard protective coating and laid them near to some food. Insect eggs are therefore similar to the seeds of plants. When the young hatched they were able to live on land. So the insects were completely free from the need for surface water to reproduce. These animals appeared about 300 million years ago. |
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Earth Earlier Earlier 300 Million Years ago Later Earth After Animals Later |
Biological Environment > Invertebrates Free From Water |
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