Snake Anatomy

A body built on ribs

A snake's skeleton is mostly a skull, a long spine and ribs. Depending on the species there can be from around 100 to over 400 vertebrae, most with a pair of ribs attached.

Some primitive snakes, such as pythons and boas, still carry tiny remnants of hind limbs visible as small 'spurs' near the vent.

Scales and shedding

Snake skin is covered in overlapping scales made of keratin. Wide belly scales (ventral scutes) grip the ground and help with movement.

As a snake grows, it sheds the outer layer of skin in a process called ecdysis. Before shedding, the eyes often look cloudy blue.

Senses

The forked tongue collects scent particles and delivers them to the vomeronasal organ, letting a snake 'smell in stereo' to follow trails.

Pit vipers, pythons and boas have heat-sensing pits that detect infrared radiation from warm-blooded prey.

Snakes lack external ears but sense vibrations through their jaw and body, and can hear some low-frequency airborne sound.

Jaws and eating

The two halves of the lower jaw are joined by a stretchy ligament rather than fused bone, and the skull bones are loosely connected, so snakes can swallow prey wider than their heads. The jaw does not actually 'unhinge'.

A tube called the glottis can be pushed forward so the snake can breathe while slowly swallowing a large meal.

Organs

Paired organs are often staggered or reduced to fit the long body. Most snakes have just one functional lung, the right one, which is greatly elongated.