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.
How many types of sharks are there? More than 450 shark species have been documented as of 2014. Sharks have been around since prehistoric times, with evidence of their existence dating back hundreds of millions of years. The first sharks appeared in the world's oceans around 420 million years ago.