Discover Scuba Diving Desirable Florida Keys Style. Exploring Florida Keys National Marine Sanctuary with PADI Inst. David & Inst. Holly. Fun Fish Fact of the day: Fish have been on the earth for more than 450 million years. Fish were well established long before dinosaurs roamed the earth. There are over 25,000 identified species of fish on the earth. Did you know fish are cold-blooded like reptiles and amphibians? They can’t control their body temperature.