Snakes are ectotherms, meaning their body temperature remains close to the environment around them, obtaining their body heat from external sources. In cooler climates, snakes will hibernate during winter. However, in warmer climates, they will shelter in rock crevices and logs during cooler weather, and leave these spots to soak up the suns warmth when it is available.
Snakes are less active during cold weather, therefore will hunt less. Their metabolism also slows down during winter; they use up their stored body fat from the warmer months.
The body temperature of snakes plays a vital role in their overall health and well-being, aiding in digestion, activity levels and breeding. Their environmental temperature also plays a role in their hibernation habits.
Vision
A snake's eyesight varies from extremely poor to good, depending on whether the species are nocturnal (night) or diurnal (day). Snakes have difficulty seeing motionless prey or enemies; therefore, a snake's vision is mainly used in the detection of movement. Objects at 40 feet may appear blurry to snakes, while at 10 or 15 feet, these same objects will appear clearer. A great difference between the sight of snakes and other animals is that other animals are able to focus on an image on the retina of the eyes by using a special muscle to change the shape of the lens; these muscles are absent in many snakes.
Nocturnal species tend to have smaller eyes, resulting in less clear vision. For this reason, nocturnal snakes generally rely heavily on their other senses (especially scent and body heat). Diurnal snakes, possessing larger eyes, tend to rely more heavily on their vision.
Snake Eye Characteristics
Snakes' top and bottom eyelids are fused together, preventing them from being able to close their eyes or blink (this is the reason why snakes appear to stare at their prey). Each eye is covered with a single clear scale (called a 'brille'), which aids in protecting the eyes from injury and drying out.
The eye scales of snakes are a part of their skin, which means that as they shed their skin, the eye scales will also be shed. Prior to shedding, the snake's skin becomes dull and the eye scales become cloudy due to secretions of a milky fluid between the old skin and the new skin.
Hearing
Snakes do not possess external ears (therefore do not have eardrums or middle ears). However, they do possess one ear bone (called a columella), which is attached to their jaws. The columella detects sound vibrations traveling along the ground.
Smell
Snakes are one of the few animals that is capable of smelling with their forked tongues. While snakes do possess nostrils and nasal cavities, they are not used to smell; instead, it is their tongues that are used to smell or sniff the air.
An organ, known as the 'Jacobson's organ' (located on the roof of a snake's mouth), picks up and traps tiny particles in their air, which are then transferred to the mouth.
Heat Sensing Pits
Snakes such as vipers, rattlesnakes and other snakes from the viper family, possess two special heat sensors, called 'pits'. These pits are located between the snake's eyes and nostrils, and are used to detect heat given off by warm-blooded prey. These pits provide snakes with the ability of knowing how large or small the prey is, and of its exact location.
Source
Taylor B, O'Shea, M. 2004. The Great Big Book of Snakes & Reptiles. Annes Publishing Ltd: London
Edwards, B. 2003. An Introduction to Australian Snakes. Penon Publishing. Niddrie: Melbourne, Australia.
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