Final answer:
Aquatic vertebrates use gills for salt and water exchange, while terrestrial vertebrates primarily use the kidneys. However, the skin and lungs also play a role in osmoregulation.
Step-by-step explanation:
Major Routes and Organs for Salt and Water Exchange in Vertebrates
In aquatic vertebrates, such as fish, the gills are the main organs for salt and water exchange with the environment. Fish living in freshwater take up water through their gills and excrete dilute urine to maintain electrolyte balance. In contrast, marine fish drink seawater and excrete excess salts through their gills and urine.
In terrestrial vertebrates, such as mammals, the kidneys are the main osmoregulatory organs. The kidneys filter blood and generate urine, which helps in maintaining water and electrolyte balance. However, the skin and lungs also play a role in osmoregulation by losing water and electrolytes through sweat glands and mucous secretions.