• Question: Why do fish lay so many eggs?

    Asked by puggy1 to Adam, Joanna, Louise S, Louise W, Marcus on 20 Nov 2012.
    • Photo: Marcus Wilson

      Marcus Wilson answered on 20 Nov 2012:

      unlike us fish fertilisation happens outside of the body. whilst we can control what happens to us inside the body, if you lay eggs outside you cannot account for whats going to happen to them.

      fish get round this probelm by just producing lots of eggs, if soem are swept away or are eaten, it doesnt matter beacuse theres many more of them around.

    • Photo: Adam Paige

      Adam Paige answered on 20 Nov 2012:

      Evolution favours individuals that are very good at passing on their genes to offspring. The genes that make an individual best at reproducing and raising offspring will be the genes that are most common in the next generation.

      For some species, the best way to ensure your offspring survive is to have only one or two, and then look after them really carefully. Staying with them, feeding them, nurturing them and protecting them. For example, birds and mammals.

      For other species, there may not be enough food to risk the parents and children living in the same place. Or the dangers of getting eaten may make it too risky to stay together. In these species, it is much safer to give birth to lots of offspring and then leave them to look after themselves. Although many will die in their dangerous environment, some will likely survive and form the new generation. This is how fish and spiders reproduce.

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