Egg Size Relationship
How is the size of an egg determined?
In chick, the egg contains all the essential nutritients & energy for the
development of embryo.
The egg yellow you see is the ovum (the female sex cell)that is stuffed with
yolk. Yolk provides much of the energy for the development.
The size of the egg among egg laying birds & reptiles are determined by the
total energy required for the complete development of the embryo. The
developed young one then breaks open the shell and comes out.
Among insects say for example, the eggs are too small. In such animals the
eggs have energy just for partial development. The egg develops into a
larva. The larva (a stage of the developing embryo) then feeds voraciously
to acquire energy then develops into a pupa (cocoon) and then into a fly!
Often the size of the egg is determined by the size of the bird laying the
egg. Ostriches have huge eggs, while robins eggs are much smaller. It also
depends on how developed the baby bird will be once it comes out. If the
species of bird tends to be more developed when hatching, the egg would be a
bit larger than one in a species were the baby would be less developed.
There's no simple answer. Small birds tend to have larger eggs in proportion
to their body weight than large birds. Eggs of precocial birds, like ducks,
who hatch out ready to move about and feed themselves, are proportionally
larger than those of altrical birds, like robins, that are helpless when
they hatch. That is because more energy has to be invested in the eggs of
precocial birds, where more energy is invested in raising the nestlings of
altrical birds. Nutrition also plays a role. Within a species, females who
have better nutrition produce larger eggs than those with poor nutrition. I
do not have any information at hand on reptile or amphibian eggs, if you
have more questions ask again.
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Update: June 2012