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Why do animals with EXTERNAL fertilisation (such as fish and frogs) typically release HUNDREDS of eggs and millions of sperms at a time?
AThey cannot count their eggs
BEggs need to be packed tightly to survive
CMore eggs taste better to predators
DOnly a small fraction of eggs and sperms successfully meet and develop, because of water currents, predators and weather — large numbers maximise the chance that at least a few survive
Answer & Solution
Correct answer: D. Only a small fraction of eggs and sperms successfully meet and develop, because of water currents, predators and weather — large numbers maximise the chance that at least a few survive
In external fertilisation, eggs and sperms are released into open water. Many are washed away, eaten by other animals, or never meet. Producing huge numbers compensates for this very low individual survival rate. Internal fertilisers (cow, human, hen) produce far fewer eggs because each egg has a much higher chance of becoming a viable offspring.
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