Why haven't whales evolved gills?

Thread starter Jupiter60
Start date Sep 1, 2015

AI Thread Summary

Whales have not evolved gills because they are mammals that breathe air using lungs, which provide a more efficient oxygen exchange than gills. Their evolutionary lineage traces back to terrestrial mammals, and they have adapted to their aquatic environment without the need for gills. The metabolic demands of whales, which are warm-blooded and require high oxygen intake, make gills incompatible with their physiology. Additionally, the risk of hypothermia from water exposure further complicates the viability of gills for large marine mammals. Overall, the absence of gills in whales reflects their evolutionary adaptations to life in water while maintaining their mammalian characteristics.

Sep 8, 2015

DaveC426913

Gold Member

DiracPool said:

Evolution isn't 100% efficient by any means, but it is by necessity, parsimonious, and the odds are vanishingly small that it would retain two mutually distinct respiratory systems, especially in larger aquatic mammals.

Perhaps not mutually distinct, but many animals have multiple respiratory systems. The common Bettafish and the Gourami have what's called a labyrinthine organ, allowing them to breathe air. (In fact, they must breathe air, or they will drown. They still use their gills, it's just that the gills aren't sufficient.)