Exhibiting a wide range of variations, over 100 species of antelopes have been classified. Shoulder heights can range from 12 inches (pygmy) to 6 feet (giant eland). Also, their hollow horns vary from very short to very long, straight to curved, and ringed to spiral. One uniting characteristic is that antelopes are all fast runners. They are second only to the cheetah, reaching 60 mph and they have been rumored to reach even 70 and 80 mph. Antelopes are capable of reaching such speeds because of oversized tracheas, huge lungs and hearts that lend them the power to consume and process large amounts of oxygen.