Air-breathing and excretory nitrogen metabolism in fishes.

摘要: During water-land transition, ancient fishes acquired the ability to breathe air, but air-breathing engendered problems in nitrogenous waste excretion. Nitrogen is a fundamental component of amino acids, proteins, and nucleic degradation these nitrogen-containing compounds releases ammonia. Ammonia toxic must be removed. Fishes water excrete ammonia as major through gills, gills are modified for or largely replaced by organs. Notably, emerged from can no longer effectively because lack flush gills. Hence, that participated transition have developed means deal with toxicity. Extant fishes, particularly amphibious ones, serve models examine adaptations which might facilitated emergence water. Some actively emerge display complex behaviors on land, while few burrow into mud survive years during drought. Many them equipped mechanisms ameliorate toxicity emersion. In this review, adopted emersion were organized seven disparate strategies. addition, eight extant distinctive terrestrial peculiar natural habitats selected describe detail how strategies could combinations