Doctors sometimes run tests even when they know you’re just fine. The tests tell them how your body works when it is fine, making it easier to figure out what’s wrong when you’re sick.
Marine biologists sometimes do the same thing with fish. They run tests to see how the fish operate under current environmental conditions. That can help them figure out how the fish are faring in the future under different conditions.
When most people hear “shark,” they picture a large, sleek-bodied predator slicing through the open water, perhaps with the triangle of its dorsal fin poking through the surface as a warning. But there are more than 1,000 species of sharks of all shapes and sizes—including some small sharks that are adapted to living in very shallow water.
