How do turtle eggs breathe?

A sea turtle nest has the advantage of being between several inches (15 cm or more at the top) and a yard (1 meter) below the surface of the sand. Temperature moderates as depth increases both in terms of absolute value and daily fluctuation. The water content of the sand remains stable deep within the nest even if the sand dries near the surface. The main problem in laying eggs is getting enough oxygen to carry out metabolism and get rid of the carbon dioxide produced in the breath. Oxygen is transported in the air and sand surrounding the nest to the nest within the nest by a process known as diffusion. Carbon dioxide is transported in the same way.

Fick’s law of diffusion defines the process. The movement of material by diffusion depends on the driving force that exists between an area of ​​high concentration and an area of ​​low concentration and the resistance of the path between the source and the sink. In the case of a turtle nest, sand provides most of the resistance because the eggshell is relatively porous to the flow of gases. In some cases, oxygen can drop from 20.9% in air to 20.4% in sand due to metabolism by bacteria in sand and 12-14% in the middle of the brood just before hatching . However, the oxygen level in the clutch is similar to that in the alveoli of the human lung.

One of the reasons leatherback turtles lay their eggs in the dry season is that the dry layer that forms on the surface of the sand helps to transport gases more easily between the air and the nest. The olive ridley nests on the arribada beaches suffer from low oxygen levels due to the high density of the nests on the beach and the decomposition of the broken eggs during the arrivals.

It is amazing that a clutch of sea turtle eggs can survive buried between 10 and 36 inches under the sand. The oxygen must diffuse from the air into the sand and into the egg. Carbon dioxide must move in the opposite direction. A developing sea turtle embryo breathes through its shell just like a chicken embryo, which has the same concentrations of oxygen and carbon dioxide within its shell as in the human lung. Sea turtle eggs have similar internal gas concentrations, but there is a difference. The turtle eggshell is very porous, which facilitates the movement of gases, while the chicken eggshell is very resistant. Gas concentrations in sea turtle eggs are determined by the speed at which air can move through the sand and into the egg. Oxygen seeps through almost a meter of sand, through the pores between the sand grains, then between the eggs in the clutch, and finally to the egg in the middle of the clutch. The main barrier is the speed of air movement between the sand grains. That meter-long layer of sand works essentially like a chicken’s eggshell or human air passes into the lung. It serves as an airway for the sea turtle egg.

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Category: Pets