The tiger has a muscular body with powerful forelimbs, a large head and a tail that is about half the length of its body. Its pelage is dense and heavy, and colouration varies between shades of orange and brown with white ventral areas and distinctive vertical black stripes that are unique in each individual.
Stripes are likely advantageous for camouflage in vegetation such as long grass with strong vertical patterns of light and shade.
The tiger is one of only a few striped cat species; it is not known why spotted patterns and rosettes are the more common camouflage pattern among felids.
A tiger’s coat pattern is still visible when it is shaved. This is not due to skin pigmentation, but to the stubble and hair follicles embedded in the skin, similar to human beards (colloquially five o’clock shadow), and is in common with other big cats.
They have a mane-like heavy growth of fur around the neck and jaws and long whiskers, especially in males.
The pupils are circular with yellow irises. The small, rounded ears have a prominent white spot on the back, surrounded by black.
These false “eyespots”, called ocelli, apparently play an important role in intraspecific communication.
The white tiger lacks yellow pigments, has dark sepia-brown stripes and blue eyes.
This altered pigmentation is caused by a mutant gene that is inherited as an autosomal recessive.
It is not an albino, as the black pigments are scarcely affected.The mutation changes a single amino acid in the transporter protein SLC45A2.
Both parents need to have the allele for whiteness to have white cubs. Between the early and mid 20th century, white tigers were recorded and shot in the Indian states of Odisha, Bihar, Assam and in the area of Rewa, Madhya Pradesh.
The local maharaja started breeding tigers in the early 1950s and kept a white male tiger together with its normal-coloured daughter; they had white cubs.
To preserve this recessive trait, only a few white individuals were used in captive breeding, which lead to a high degree of inbreeding.
Inbreeding depression is the main reason for many health problems of captive white tigers, including strabismus, stillbirth, deformities and premature death.
Other physical defects include cleft palate and scoliosis.
True albino tigers do exist and may be termed “snow white” tigers. In this colour morph, the stripes are extremely faint on the body while the tail has pale reddish-brown rings.
Golden tigers, another colour morph, have pale golden pelage with a blond tone and reddish-brown stripes. These types are rarely recorded in the wild. Both snow white and golden tiger are homozygous for the CORIN gene.