Question

Explain the challenges the vertebrates faced in moving from water onto land and give a ‘solution’ or response to each challenge that can be seen in modern reptiles.

Answer 1

During the Paleozoic Era (542 to 251 million years ago), the first vertebrates were gradually transitioning to life on land. Hence they faced the following challenges -  

Challenge 1: Being able to derive oxygen from the air instead of from the water.

Solution - Because reptiles are ectotherms (temperature regulation on the basis of environment) hence need for energy is less than endotherms(temperature regulated internally ) so they have mixed circulation i.e. impure blood mixes with pure blood.

Challenge 2: Differing in terms of food on land vs water .

Solution - The land vertebrates need more energy hence they have fast digestion as in birds and mammals but reptiles needs less energy hence their digestion is slow for less metabolic need of theirs.

Challenge 3: Aquatic animals in water feel lighter because of the buoyant force. Living on land makes it difficult to roam around, which takes more energy than they have.

Solution - The four-chambered heart of birds and mammals seperating oxygen rich blood and oxygen deficient blood , it forms efficient circulatory system.

Reptiles need less energy being endotherms hence they have three chambered heart.

Challenge 4: Developing sensory mechanisms for dealing with life on land versus life in the water.

Solution - The cognitive abilities of reptiles are weaker than land animals but they have larger cerebrum and cerebellum which compensates the difference they face in response of the smell , sight , vision and light.