- Scales on the underside of the snake (venter scales) provide the contact
edges essential for the snake to move. At the end of the venter scales
is an anal plate which protects the opening to the cloaca. The cloaca
is a shared opening for waste and reproductive material to pass.
- Snakes have dry keratinous scales. The size, arrangement, and number
varies by species and location on the body. Generally, scales on the
head are larger on top, smaller and more numerous on the sides and around
the mouth and chin.
- Body scales usually lie in linear rows with each having a fixed number
of scales, typically an odd number ranging from 13 to 27. This number
is species specific.
- The body of the snake contains a string of vertebrae (bones that
make up the spine). Typically, there are more than 120 in the body and
tail and in some species as many as 585.
- Snakes are more closely related to lizards than to other reptiles,
and probably evolved from a single group of lizards. Curiously, they
probably did not evolve from the group of legless lizards.
- Many snakes, such as vipers, boas and pythons have temperature-sensing
organs on their heads. These heat pits are sensitive to changes in temperature
of as little as 0.002 degrees Celsius, and effectively allow the snake
to navigate and hunt in the dark.
- Snakes can have over 300 pairs of ribs.
- Snakes turn "blue" before a shed. This opaque change to
the skin is actually due to the presence of a lymph-like layer of fluid
between the old and new skins, prior to the shed of the old skin.
- The smallest snake may be the Martinique thread snake (Leptotyphlops
bilineatus), which does not grow any bigger than 4 1/4 inches.
- The glottis, which is the entry to the trachea (breathing tube), can
move to either side, to allow the snake to swallow prey. This is the
tube you see when you look at the floor of a snake's mouth. Cartilage
around the opening of the tube closes to prevent food from entering
the respiratory tract, and produces the classic "hiss" in
many snakes.
- A snake's heart can slide 1 to 1 1/2 times its length from its normal
position, to allow the passage of swallowed prey. This is because of
the relative mobility of the pericardial sac, which surrounds the heart.
- Venom glands have evolved independently in several species. Venoms
are very complex substances, which may consist of a dozen or more toxic
components. These can include substances poisonous to the heart, nerves
and DNA as well as enzymes that break down natural tissue barriers,
allowing the spread of venom within the body.
- Snakes have two rows of teeth on the top jaw, one row on the bottom
jaw. The teeth, including fangs, in most cases are replaced throughout
life.
- Snakes move by relaxing and contracting muscles lengthwise along the
body. Sidewinding is a specialized form of motion that allows a snake
to travel with speed and relatively little expenditure of energy along
loose desert sand. The snake lifts a loop of its body from the surface,
using its head and tail. The loop is moved sideways and then back to
the ground. This creates the typical series of unconnected parallel
tracks.
- The paired claw-like structures seen on either side of the vent of
a snake such as a ball or royal python, are in fact, remnants of the
legs present in the animals from which the modern species has evolved.
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