Tigers 101 | National Geographic

With their signature orange fur and black stripes, tigers have become icons of beauty, power, and the importance of conservation. Tigers have evolved into six subspecies. The tiger's tale of evolution can be traced back to about two million years ago when the earliest known tiger ancestor left Africa and ventured into Asia. Over time, the big cat split into nine subspecies, with six still alive today.

The most numerous subspecies is the Bengal tiger, accounting for approximately 50 percent of the tiger population worldwide. Tigers are the world's largest cats; on average, the big cats weigh about 450 pounds. But the largest is the Siberian tiger subspecies, measuring up to 13 feet long and weighing up to 660 pounds. This extra weight is primarily because of large, powerful muscles. Unlike lions, the second largest of the big cats, tigers have more muscle mass and are therefore heavier.

Tigers have webbed toes, often living near bodies of water. Tigers have adapted for a semi-aquatic lifestyle. They appear to enjoy being in the water, unlike most cats, and are excellent swimmers, using their powerful muscles to propel their bodies in the water. They've also evolved to have webbing between their toes. The webbing allows the big cats to push around a greater volume of water with each stroke of their paws.

White tigers are a type of Bengal tiger. The classic black and orange coloration of most tigers is caused by the pigments eumelanin, which turns fur black, and pheomelanin, which turns fur orange. The production of pheomelanin is triggered by the gene SLC45A2. White tigers carry a mutated version of this gene, which prevents them from producing orange pigmentation.

Fewer than 4,000 tigers remain in the wild. At the turn of the 20th century, approximately 100,000 tigers roamed the wild, living as far west as Turkey and as far north as Russia. But due to deforestation, human development, and poaching, their range severely decreased, and within 100 years, the world's tiger population declined by about 96 percent.

Over the past few decades, programs have been put in place to protect tigers and their habitats. With the help of the global community, tiger populations may slowly rebound.