Why do fish and frog lay more number of eggs whereas cow and human beings usually give birth to only one at a time ?
Answers
Answer:
Fish and frog fertilize their egg by external fertilization and cow and human beings fertilize their egg by internal fertilization. Fish and frog lay a greater number of eggs at a time because their fertilization is external whereas fertilization in cows and human beings is internal. Due to external fertilization in fish and frog, the eggs are at risk of getting destroyed by the environmental factors and predators. Survival rate of the eggs is less in organisms that reproduce by external fertilization. Fish and frog are oviparous. This is why they lay thousands of eggs, to maintain their species.
Cow and human beings are viviparous and they fertilize their egg by internal fertilization. It protects the fertilized egg from external harsh environment. Survival rate of young ones is higher in internal fertilization. Generally. embryo is protected inside the mothers’ body. The fertilized egg is protected from the environmental damage and predators. That’s why cows and human beings usually give birth to only one at a time as one zygote is very safe in mother’s womb.
Answer:
External development of young ones occurs in case of frog and fish due to which its protection from the surrounding decreases. So to cope up with the loss they lay more no. of eggs because not many have a chance to survive. Whereas in case of cow and human beings development occurs inside the mother’s body and the egg is protected. So they give birth to only one at a time.
Explanation:
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