Patrons feed lettuce to a male Masai giraffe at the Cleveland Zoo, one of the Cleveland Metroparks in Cleveland, Ohio, in the United States.

There is only one species of giraffe, but nine sub-species.

There are just 23,00 Masai giraffes left in the wild. The population has declined 52 percent in the last 30 years due to hunting and poaching.

The Masai giraffe (Giraffa camelopardalis tippelskirchii), also called Kilimanjaro giraffe, is the largest subspecies of giraffe. It is the tallest animal in the world, with females reaching 17 feet and males 20 feet in height.

The Masai giraffe is native to East Africa and has distinctive, irregular, jagged, star-like blotches which extend to the hooves.

All giraffes are born with horns, which are made or bone (not cartilage or keratin, as with rhinos or deer). The horns on males are bare, while female horns are tufted. In Masai giraffes, a lump between the horns is usually present in males.

Females come into heat every 12 to 15 days and give birth once every two years. The average gestation period is 457 days. The number of offspring is almost always one, though twins do occur. Calves are weaned at around 12 months, and are sexually mature about age 5 (for females) to 7 years (for males). Giraffes live 20 to 25 years in the wild, although they often live to age 30 or more in captivity.

Giraffes spend 17 to 20 hours a day browsing. They need only 5 to 30 minutes of sleep in a 24-hour period. They usually sleep standing up, napping for only a minute or two at a time. When a giraffe is young, or feeling very secure, it may lay on the ground and rest its head on its rump to nap.

A giraffe's tongue is 18 to 20 inches long, and blue-black in color. The tongue and lips are prehensile, allowing it to eat leaves from spiky or thorny trees.

Giraffes have excellent eyesight, hearing, and smell. They are swift runners, and can go from zero to 35 mph in less than two seconds. Giraffes are good jumpers, but cannot swim.