All members of the cat family are very similar in shape though they have different size. There are 37 species in cat family in the world today. Zoologists generally group the cat family in 3 classes: small cats, big cats and the cheetah. "Small cats" include 28 species cats such as Canadian lynx, Spanish lynx, bobcat, black-foot cat, puma, and so on. "Big cats" includes lion, jaguar, leopard, tiger, and snow leopard. The cheetah is in a class all on its own because there are no other surviving members of its group. Anyway, all members of the cat family are perfect and supreme hunters. They have lean and muscular bodies, so they can run with fast speed when they prey. They have good sense of sight and hearing, they can see at night or when the light is low. The cats have long, highly sensitive whisker, these aid them to be aware of any obstacle that may be in their way when they stalk. All the cats---except the cheetah---have retractile claws. The claws enable to draw back when walking, so their footsteps cannot be heard and the claws are kept sharp. The cheetah is the fastest land animal in the world, it can reach speed of 110 kilometers per hour. A lion can pull a prey with 270 kilograms. These best hunters are important in food chain. Unfortunately, many species of the cat family, especially the big cats, being die out today. Human kill them because the furs of many of the cats are considered attractive, the bones of the cats are considered medicinal. Before World War II there are 40,000tigers in India, and now the number is around 1,000. In 1900, there were 10,000 cheetahs in earth, today there are around 1,200, and 10 G are kept in captivity. In a word, the cats (feline) are flawless classics, which has evolved in nature, and they play an important role in keeping the ecological balance. If human don't stop to hunt them, our children will see most species of cat family only in photos.