What are the problems that vertebrates needed to solve to adapt to the terrestrial environment since they came from the aquatic habitat? How does evolution solved those problems?

1 year ago

The main problems vertebrates coming from water needed to solve to adapt to the terrestrial environment were the following: the problem to avoid dehydration; the problem of elimination of wastes in a medium where water is less available; the problem of protection against nocent solar radiation; the problem of gamete locomotion in the  environment for fecundation; the problem of gas exchange, earlier done by direct contact of water with gills; the problem of body support, since it was water that played this role in fishes.

Solutions for the dehydration problem: thicker and impermeable skin, to lose less water, or moist and permeable skin, like in amphibians. Solution for the excretion problem: excretion of urea (also excreted by chondrichthyes) or uric acid, substances that need less water to be dissolved. Solutions for the problem of protection against radiation: skin pigments that filter harmful radiation, feathers, hair or carapaces.

Solution for the gamete movement problem: internal fecundation (except for most amphibians, that have external fecundation). Solution for the gas exchange problem: appearing of airways and lungs. Solution for the body support problem: further development of muscular and bony structures, like limbs and claws.

Dipti KC
May 18, 2023
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