Size

Cline Morphology

Four out the five living tiger subspecies' morphology (physical structure and appearance) exhibit a cline. A cline occurs when a single species gradually begins to look different over its geographic distribution as it adapts to varying climates and habitats. Therefore the species at the northern end of their geographic distribution may look very different in size, color, hair-density, etc. than their southern counterparts. The Tiger cline depicts subspecies decrease in size and have darker stripe coloration the further south their range extends.

The largest tigers are found in the north, gradually becoming smaller in the south.

• Adult male Amur tigers (Panthera tigris altaica) may weigh up to 300 kg. (660 lbs.) and measure about 3.3 m. (10.9 ft) in length. Females are smaller, weighing between 100 to 167 kg (200 to 370 lbs.) and measure about 2.6 meters (8.5 ft) in length.
• Adult male Bengal tigers (Panthera tigris tigris) weigh about 220 kg (480 lbs.) and measure about 2.9 m (9.5 ft) in length. Females are slightly smaller with an average weight of 140 kg (300 lbs.) and 2.5 m (8 ft) in length.
• The South China tiger (Panthera tigris amoyensis) are native to South Central China. Males weigh about 150 kg (330 lbs.) and are about 2.5 m (8 ft) in length. Females weigh are smaller, weighing about 110 kg (240 lbs.) and are about 2.3 m (7.5 ft) in length.
• Adult male Indo-Chinese tigers (Panthera tigris corbetti) may weigh up to 182 kg (400 lbs.) and measure about 2.8 m (9ft) in length. Females are smaller, weighing about 115 kg (250 lbs.) and measure about 2.4 meters (8 ft) in length.
• Adult male Sumatran tigers (Panthera tigris sumatrae) may weigh up to 120 kg (265 lbs.) and measure about 2.4 m (8 ft) in length. Females are slightly smaller, weighing about 90 kg (198 lbs.) and measure about 2.2 m (7 ft) in length.

Legs, Feet & Claws

The hind legs of the tiger are longer than their front legs. This characteristic enables them to leap forward distances up to 10 meters (32.5 ft).

The bones of the tiger's front legs are strong and dense to support the large musculature needed to take down large prey.

The bones in each of the tiger's feet are tightly connected by ligaments enabling them to buffer the impact of landing from running, pouncing and leaping.

Tigers have large padded feet that enable them to silently stalk prey in the Asian jungles.

The claws of the tiger are up to 10 centimeters (4 in) in length and are used to grasp and hold onto prey. Each paw has four of these claws and one specialized claw called a dewclaw. A dewclaw is located farther back on the foot and thereby does not touch the ground when walking. Dewclaws function similarly to thumbs in that they are used for grasping prey and aid in climbing.

Tiger claws are retractable in that ligaments hold them in a protective skin sheath when their not being used. The ligaments are in a relaxed position when the claws are retracted thereby expending no musculature effort. Tigers retract their claws to ensure that they remain sharp for times when they are needed and to tread silently up to unsuspecting prey. Other ligaments will extract the claws when attacking prey or defending themselves which does require musculature effort.

Tiger claws are curved which enables them to superiorly grasp and hold large prey and climb trees head-first. However, the claws' curvature, the tiger's size and weight is a great hindrance in climbing down from trees. Tigers must either crawl backwards or jump down from trees, making them the most inferior climbers of the big cat family.

Head & Collarbone

The skull of the tiger is stout and rounded in shape which provides more support for their powerful jaws.

Tigers' powerful jaw muscles are attached to a bony ridge that lay on top of the skull called the sagittal crest. These muscles function to rapidly clamp down on prey with crushing force.

Tigers have a reduced-sized clavicle (collarbone). This characteristic enables them to attain greater stride lengths because the smaller clavicle allows for a wider, unrestricted range of movement of the scapula (shoulder blade) when running.

Dentition

Tigers have fewer teeth than other carnivores such as dogs (42 teeth) with only 30 teeth.

All cats have deciduous (temporary) teeth that come in within a week or two after birth. These teeth are referred to as milk teeth similar to humans' baby teeth. The milk teeth are eventually replaced by the permanent ones. Therefore they are seldom without a set of teeth.

Tigers have the largest canines of all big cat species ranging in size from 6.4 to 7.6 centimeters (2.5 to 3.0 in) in length. The canines have abundant pressure-sensing nerves that enable the tiger to identify the location needed to sever the neck of its prey.

The back teeth of the tiger are called carnassials which enables the tiger to shear meat from their prey like knife blades. They swallow large-sheared pieces of meat whole.

Tigers are capable of penetrating deeply into their prey because of the large gap between the carnassials (back teeth) and the canines hold prey tightly.

The small incisors located in the front of the mouth (between the two top and bottom canines) enable the tiger to pick off meat and feathers from their prey.

Digestion

The process of converting meat to protein (needed for energy) is significantly less complicated in carnivores than it is to convert grass to protein as some herbivores require. Carnivores do not require the vast amount of microbes (microscopic bacteria) living in their intestines to break down indigestible plant cellulose. Therefore tigers and other carnivores have small and light weight stomachs that do not hinder them when they are accelerating quickly to chase prey.

Tail

A tiger's tail is about one meter in length (3 ft) and may play a part in their visual communication (see communication- vision section).

Tigers use their tail for balance when making sharp turns in pursuit of prey.

Tongue

The tiger's tongue is covered with numerous small, sharp, rear-facing projections called papillae. These papillae gives the tongue is rough, rasping texture and is designed to help strip feathers, fur and meat from prey.

Hair & Coloration

The hair of the tiger provides camouflage, warmth and protection for them.

Tigers possess two types of hair, guard hair and underfur. The guard hairs are longer and more durable than the underfur and mainly function for protection purposes. The primary function of the tiger's hair is for warmth. The underfur traps air which insulates the tiger's body thereby keeping it warm.

Tigers are the only large cat species to have distinctive striping located on both the hair and skin of the tiger.

Many tigers possess stripes on their face, sides, legs and stomach. The striping is varied in width, length, whether they are single or double-looped, coloration from a light brown to dark black and are not symmetrical from one side of the tiger to the other.

The stripe patterning on top of the tiger's head resembles the Chinese character of "wang" which means "king."

Tiger Background Coloration:

• Many tigers possess the light yellow-orange to deep reddish-orange background coloration.
• Black or melanistic colored tigers have been reported but further research is required before assessing whether these sightings were of true melanistic tigers or darker versions of the orange tiger (with few large broad dark stripes).
• Tigers with white background coloration are not considered albinos. An albino would be pure white in color (no striping) and would have pink or red eyes. White tigers are leucocystic meaning that they have a recessive gene that causes them to lack dark colors. Therefore they usually have a white color with light to medium brown striping and blue eyes. For unknown reasons, white tigers seem to grow bigger and at a faster rate than their orange counterparts.

There have been reported sightings of blue tigers. There is little evidence supporting this color variation in tigers. However, since the blue colored trait exists in some lynx and bobcat families; it is not ruled out as a possibility.

Tigers have distinctive white circular spots on the backside of their ears. There are two ideas as to the function of these eyespots. One of which is that they function as "false eyes"; making the tiger seem bigger and watchful to a potential predator attacking from the rear. The other idea is that they play a role in aggressive communication because when threatened tigers may twist their ears around so that the backs face forward. This prominently displays the distinctive white markings. The function of the white markings is probably a combination of both ideas.