how is the mudskipper, which is a fish and breathes through gills, able to spend a substantial amount of time out of water?

Mudskippers are found in mangrove swamps in Africa and the Indo-Pacific, they frequently come onto land and can survive in air for up to three and a half days. Mudskippers breathe through their skin and through the lining of the mouth (the mucosa) and throat (the pharynx). This requires the mudskipper to be wet, limiting mudskippers to humid habitats. This mode of breathing is known as cutaneous breathing. It is similar to the method employed by amphibians. They propel themselves over land on their sturdy forefins.

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