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.
Of the existing 368 species of sharks, only 20 are dangerous to humans. Of them, four account for almost 60-70 shark attacks registered annually worldwide. Up to 11 of these attacks are deadly. In 2006, 62 people were attacked and 4 died.