If your floor really needs more than that, consider a low-cost alternative to refinishing: Apply a fresh topcoat of nonyellowing polyurethane, found in the flooring section of a home improvement store. Be sure to very lightly sand the floors with a pole sander and fine-grit sandpaper.
There are 440 different species of sharks in the world today classified into eight different orders described below with some examples of known sharks species for each group.
Currently there are approximately 400 described species of sharks, however new species are being described all the time. In addition, there are around 400 species of rays, a close relative of sharks. Like all living things that humans know about, they are classified by kingdom, phylum, class, order, family, and species. Sharks all belong to the same class, Chondrichthyes, but they are divided into 8 different orders.