How do axolotls enhance their gas exchange efficiency?

Axolotls enhance their gas exchange efficiency primarily by breathing through their skin, which is a key adaptation for amphibians that live in aquatic environments. Their skin is highly vascularized, meaning it has a rich supply of blood vessels, facilitating the direct exchange of gases (oxygen and carbon dioxide) with the surrounding water. This method of gas exchange is efficient because it allows for a larger surface area exposed to the water compared to respiratory structures like lungs.

While axolotls do possess rudimentary lungs, they rely on skin respiration especially when submerged. This adaptation allows them to absorb oxygen more effectively in their natural aquatic habitats where oxygen levels may vary. The ability to perform gas exchange through the skin provides flexibility and increases their survival in different environments, especially when oxygen is limited in water.

Other options do not accurately describe how axolotls enhance gas exchange efficiency. For instance, using lungs exclusively would limit their ability to absorb oxygen in water, and reducing the number of capillaries would detract from their ability to facilitate gas exchange rather than enhance it. Although submerging entirely in water is an aspect of their lifestyle, it does not specify a mechanism of gas exchange efficiency like skin breathing does.