How do turtle eggs breathe?

A sea turtle nest has the advantage of being several inches (15 cm or more to the top) to a yard (1 meter) below the surface of the sand. The temperature moderates with increasing depth both in terms of absolute value and daily fluctuation. The water content of the sand remains stable deep in the nest even though the sand dries out near the surface. The main problem for a clutch of eggs is getting enough oxygen to carry out metabolism and getting rid of the carbon dioxide produced in respiration. 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 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, the 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 the air to 20.4% in the sand due to metabolism by bacteria in the sand and to 12-14% in the middle of the clutch just before hatching. However, the oxygen level in the clutch is similar to that in the alveoli in the human lung.

One of the reasons leatherbacks lay their eggs in the dry season is that the dry layer that forms on the surface of the sand helps transport gases more easily between the air and the nest. Olive Ridley turtle nests on Arribada beaches suffer from low oxygen levels due to the high density of beach nests and the decomposition of eggs that hatch during Arribadas.

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

Leave a Reply

Your email address will not be published. Required fields are marked *

Back To Top