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.
User: What inventor perfected the microscope and was the first person to see a microorganism? A. Ambroise ParÃ©, B. Andreas Vesalius, C. Robert Boyle, D. Anton van Leeuwenhoek Weegy: The inventor who perfected the microscope and was the first person to see cells and microorganisms was Anton van Leeuwenhoek. selymi|Points 16487| User: Today's Baptists, Mennonites, and Amish can all trace back to what religion?