CLEIDOIC EGG Meaning and
Definition
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A cleidoic egg is a type of egg found in reptiles, birds, and monotremes. It is a notable characteristic of amniotes, which are vertebrate animals that possess an amnion, a specialized embryonic membrane that encloses the developing embryo. The cleidoic egg is often referred to as the amniote egg due to the presence of this membrane.
The cleidoic egg is distinct from the eggs of most other animals, as it is enclosed in a thin, semi-permeable shell composed primarily of calcium carbonate. This calcified shell provides protection to the developing embryo, shielding it from predators, desiccation, and mechanical stress. It also helps to maintain a stable environment, limiting gas exchange while allowing for the diffusion of gases necessary for respiration.
The amnion, located beneath the shell, is filled with amniotic fluid, which bathes the developing embryo and provides a cushion against mechanical shocks. It also serves as a medium for various metabolic processes. The amniotic fluid further prevents desiccation, allowing the egg to be laid in terrestrial environments without drying out.
Overall, the cleidoic egg represents an evolutionary adaptation that enables amniotes to reproduce and thrive on land. By enclosing their embryos within protective membranes and developing specialized mechanisms for obtaining oxygen and disposing of waste, amniotes have successfully colonized diverse habitats around the world.
Etymology of CLEIDOIC EGG
The word "cleidoic" comes from the combination of two Greek roots: "cleis" meaning "lock" or "key", and "oikos" meaning "house" or "enclosure". The term "cleidoic" is often used to describe a type of egg that is enclosed within a protective shell.
