Why has no tetrapod re-evolved gills?

(writing in progress)

Various lineages of tetrapods, after extensive modification for terrestrial life, have evolved to re-enter the water (foraging entirely underwater).

These include

All of these forms have evolved streamlining and fin-like flippers. However, all retain lungs, and none has re-evolved gills.

Therefore, all aquatic tetrapods are limited by the need to return to the surface each time they inhale.

Why have gills not re-evolved?

Posted on Αύγουστος 24, 2023 0535 ΠΜ by milewski milewski

Σχόλια

Αναρτήθηκε από milewski 6 μήνες πριν

Why gills? Why not any other form of water gas exchange - e.g. via the anus or tail, or elsewhere on the body?

Αναρτήθηκε από tonyrebelo 6 μήνες πριν

Because gills are too leaky. Too high osmotic costs. Air is far more efficient. And oxygen can readily be stored in blood and muscles ...

Αναρτήθηκε από tonyrebelo 6 μήνες πριν

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