Knut Schmidt-Nielsen was a very smart scientist who studied how different animals live and function in their environments. He liked to study things like how animals breathe, drink water, and maintain their body temperature.
Imagine you are a bird, and you need to fly very high up in the sky to get away from danger or find food. But, the higher you go, the colder it gets. Knut Schmidt-Nielsen would study how you, as a bird, can maintain your body temperature in the freezing cold air so that you don't get sick or die.
Or, imagine you are a camel, living in the hot desert where it hardly ever rains. You need to be able to survive without a lot of water. Knut Schmidt-Nielsen would study how you, as a camel, could drink water and store it in your body for long periods so that you didn't get dehydrated and die.
Knut Schmidt-Nielsen was very interested in how creatures have adapted and evolved over time to live in different environments. He was a very important scientist, and his work helped us understand how animals can survive and thrive in conditions that would be very difficult for humans.