River otters primarily eat fish. They are also known to eat whatever is easiest to find, like crustaceans, mollusks, insects, birds, oysters, shellfish, crabs, crayfish, frogs, rodents, turtles and aquatic invertebrates.
1667: Robert Hooke 's famous Micrographia is published, which outlines Hooke's various studies using the microscope. 1675: Enter Anton van Leeuwenhoek, who used a microscope with one lens to observe insects and other specimen. Leeuwenhoek was the first to observe bacteria. 18th century: As technology improved, microscopy became more popular among scientists. Part of this was due to the discovery that combining two types of glass reduced the chromatic effect.
In 1986, the Nobel Prize was awarded to Ernst Ruska for his design of the first electron microscope, and to Gerd Binnig and Heinrich Rohrer for the design of the scanning tunneling microscope (STM).se of Microscopes. When most people think of microscopes, biology and medicine probably come to mind. And the desire to learn about living things was most likely the main reason for the invention of the microscope. Today, however, microscopes are used in many other fields.