Final answer:
Marine birds are unique in their ability to extract water from air by osmosis. They have adaptations that allow them to survive in water-scarce environments, such as their ability to drink saltwater and excrete excess salt.
Step-by-step explanation:
The animals unique in their ability to extract water from air by osmosis are marine birds. These birds have adaptations that allow them to survive in environments where water is scarce, such as their ability to drink saltwater and excrete excess salt through specialized glands. For example, marine iguanas in the Galapagos Islands sneeze out water vapor that is high in salt to maintain their solute concentrations while swimming in the ocean.