Are there senior discounts for cruise vacations?

Many cruise offering companies provide senior discounts. Here are some senior discounts from Carnival Cruises: http://www.cruiseone.com/travel/editorial.jsp/edType/Custom Page/pagename/Carnival_Senior_Specials?. Also, here is some more information on senior discounts for cruises: http://www.cruisecheap.com/cruises/senior-discounts.html