The lion is a member of the cat family, and shares many common traits of this family.
The body is very muscular, with less bone mass than other animals of comparable size. This is also responsible for the grace of movement we associate with members of the cat family. The forebody of the lion is very powerfully built, and has the greatest forebody strength of any cat, except possibly the tiger. This enables the lion to deliver blows with it's forepaws heavy enough to break a zebra's back.
Each paw is equipped with soft pads to make it's movements quiet.
Like most carnivores, lions are digitigrade walkers. This means they essentially walk on their toes. Extra bones in the toe joints give the toes a wide range of motion.
The claws are retractible and very sharp. The retractable feature helps keep the claws sharp, and prevents injury during play, etc.
The dewclaw on the front limbs is often used as a toothpick. The claws grow as a series of layers. As a layer wears, it is shed, and a new sharp-pointed claw is exposed. The claw on a large lion can be 1 1/2 inches (38 mm) or more from base to tip along the curve.
The body is covered with a sandy brown coat in most subspecies of lions,
but there is a white variant that shows up once in a while, especially in the Timbavati region of South Africa.
(The white variant is also showing up more and more among captive lion populations.)
Lions with a very dark brown coat have been observed, but this is quite rare.
The coat color of a lion is not determined so much by the color of the hair, but by the ratio of light-colored hairs to dark-colored hairs.
The mature male lion has a mane that covers the backside of the head, and the shoulders.
The extent of the mane varies from individual to individual, with some having no mane at all, while others have a luxurious mane that runs onto the body, along the abdomen, and even onto the fronts of the back legs in exceptional specimins. The mane varies in colour from the rest of the body, and tends to grow darker with age.
Some lions in the Serengeti area and from North Africa have a nearly black mane. Just like the body hair, the mane color is determined by the ratio of dark hairs to light hairs present. The mane hair is stiff and wiry, like stiff horeshair.
Besides it's primary role of protecting the male during fights, it has been discovered that female lions prefer males with bigger and darker manes.
The eyes are proportinately larger than in other comparable-sized animals, and posess round pupils.
Lions, like most cats, are visual animals.
The eyes are also well-adapted for use under very low light. This helps the lion hunt at night.
Contrary to popular notion, a lion's eyes do not glow in the dark, but they contain a special reflective coating that will reflect even moonlight.
A white circle just below the eyes helps reflect light into the eyes to further improve night vision.
Like most mammals, lions have a nictitating membrane which serves to clean and protect the eye in some circumstances. Lions, like most cats, have limited ability to move their eyes side-to-side, and must turn the head to look in a different direction.
The sense of smell is well developed.
Lions mark their territories by means of scent deposits, necessitating a good sense of smell. This also helps them find kills made by other predators, and perhaps obtain an easy meal by driving the other predator off their kill.
Another interesting thing that lions and all other cats posess is a special olfactory organ on the roof of the mouth called a Jacobson's organ. Sometimes, you will see a lion, or even your cat, grimace when smelling something. They are opening their lips to draw air over their jacobson's organs. This grimacing gesture is called Flehmen. The sense of hearing is perhaps only slightly above average. The ears can be swiveled over a wide angle to enable the lion to hear distant sounds, and know what direction they are coming from.
The lion's tail is the only one in the cat family with a tassel at the tip.
(Ligers also have a tassel, but they are not found in the wild.)
This tassel conceals a spine, which is the last few tail bones fused together.
What function this spine serves, if any, is unknown.
The tail is very important for overall balance.
Females also use their raised tail as a 'follow me' signal for the cubs. They also use it to signal each other during a group hunt.
The lion's teeth are well adapted for killing their prey and eating it.
The great canine teeth are spaced such that they can slip between the cervical vertebrae of their favorite-sized prey animals, and sever the spinal cord. The shape of the back teeth, which are called carnassals instead of molars, makes them work like a pair ofscissors, for cutting pieces of meat.
The jaw is not capable of moving side-to-side, like ours. This helps keep the carnassal teeth in alingment for cutting.
The rest of the teeth are conical, and designed for cutting and tearing. Lions, like all cats, do not chew their food, but swallow it in chunks. They also use only one side of their mouth at a time.
This trait is also common to all cats, and is caused by the inability of the jaw to move side-to-side. The tongue is covered with rough spines, called papialle. This helps the lion scrape meat off of bones, and acts like a comb for grooming.
No physical description of the lion would be complete without some mention being made about it's magnificent roar.
Only four cats can roar: The lion, tiger, leopard, and jaguar.
These four cats have been assigned to the genus Panthera because they can roar. Of these cats, the lion roars the most. It is believed the roar serves to alert other lions of an individual's presence.
Roaring choruses of several lions, or a whole pride, also take place.
When a lion roars, it can do so with enough force to raise a cloud of dust.
Roaring is made possible by a special two-piece hyoid bone in the throat.
All of the non-roaring cats have a one-piece hyoid bone.
It is said that a lion's roar can be heard 5 miles (8 km) away.