<P> In taxonomy , shark teeth are counted as follows : rows of teeth are counted along the line of the jaw , while series of teeth are counted from the front of the jaw inward . A single tooth row includes one or more functional teeth at the front of the jaw , and multiple replacement teeth behind this . For example , the jaws of a bull shark can have 50 rows of teeth in 7 series , with the outermost series functional , but most sharks have five series with the average shark having about 15 rows of teeth in each jaw . The small teeth at the symphysis , where the two halves of the jaw meet , are usually counted separately from the main teeth on either side . Sharks are also known to lose at least one tooth per week . Due to their specific arrangement of rows and series however , lost teeth can be replaced within a day . </P>
how many rows of teeth to sharks have
the average shark having about 15 rows of teeth in each jaw