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.
Simple Answer: The inventor of the first microscope is not recorded. The simple single-lens form of a microscope was in use by the 13th century by some accounts. The modern compound microscope was first developed in 1590 by the Dutch spectacle-makers Hans Janssen and his son Zacharias Janssen.More: The first microscope was merely a single lens.t is thought that around 1,000 AD use of the lens as a magnifying device was established, to this may be considered the time of the first microscope. The invention of the first lenses in spectacles to improve vision was in Italy in the 13th century.