The Egg
One question that was quite puzzling when reptiles give birth to their young alive.
Reptiles evolve to lay eggs. The egg with the calcium shell was a new trick which allows the reptiles to travel further from the water. Amphibians had to stay near the water as their eggs usually had to be laid in water. There are some exceptions.
So why did some reptiles stop laying eggs and start storing their young in their body? This has some downside for the mother which now is slower and needs more nutrients.
It turned out that there was a good reason for some reptiles not to lay eggs. Eggs are a natural incubator with a set of instructions. The problem is that the egg can have only so many fail-safes. It can get the young to hatch earlier or delay the hatching for more suitable timing.
But for the egg to work, it needs to be kept alive. Which is a problem if the ambient temperature is too low. Hence some reptiles evolved to keep its young in its body until it is time to give birth. This is offset by the advantage that most creatures will not be at their optimal speed in the cold.
Reptiles evolve to lay eggs. The egg with the calcium shell was a new trick which allows the reptiles to travel further from the water. Amphibians had to stay near the water as their eggs usually had to be laid in water. There are some exceptions.
So why did some reptiles stop laying eggs and start storing their young in their body? This has some downside for the mother which now is slower and needs more nutrients.
It turned out that there was a good reason for some reptiles not to lay eggs. Eggs are a natural incubator with a set of instructions. The problem is that the egg can have only so many fail-safes. It can get the young to hatch earlier or delay the hatching for more suitable timing.
But for the egg to work, it needs to be kept alive. Which is a problem if the ambient temperature is too low. Hence some reptiles evolved to keep its young in its body until it is time to give birth. This is offset by the advantage that most creatures will not be at their optimal speed in the cold.
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