Reptiles

We hope you enjoy this exciting information and if you encounter any terms that you don't recognize,
please be sure to check out our glossary for their meanings.

Reptiles are fascinating animals that have been on the planet for over 300 million years!
Reptiles were once the dominant species with dinosaurs ruling above mammals but now
the tides have turned and the relatively new dominant species, humans, have the
welfare of the remaining reptiles in their hands. The class Reptilia includes turtles,
tortoises, crocodilians, tuaturas, lizards and snakes. Some scientists also classify
birds in the order of reptiles, though this is up for debate.

Most reptiles are ectotherms, meaning they rely on their environments to warm and cool their bodies.

Mildly venomous Australian Whip snake, Western hog-nosed snake from North America,
and Green Tree python from South America

Snakes have 2389 known species in 11 families and 417 grenra within these families.
They typically have between 200 and 400 vertebrae (backbones). The skull is very
flexible. Contrary to popular belief, snakes to not dislocate their jaw to swallow
large prey. The bones of the upper and lower jaws are attached only with
ligaments and muscle tissue and can therefore be moved in any direction required.
When you watch a snake eat, it will move one side of its mouth up the food
item, then follow with the other side, looking like it is "walking" up its food with
its mouth. It allows the snake to eat without the benefit of hands. A snake's
teeth, no matter how small, are all curved, inwardly pointing needles which
hold the prey in place and help move it back into the the snake's throat.
The snake also has no pectoral girdle or sternum (if you feel your chest where
your ribs all meet in the middle, that's your sternum) and so they can eat
prey which is larger than their head or body width.

Snakes use the large scales on their bellies, called "scutes", to help propel them
forward. All snakes move on land with the help of these scutes and all snakes
can also swim, though many prefer to be land based most of the time. Some
snakes spend practically all their time in the water, however, and are often
extremely poisonous. Snakes have 4 styles of movement: rectilinear, which
allows them to move in a relatively straight line; the lateral undulatory
method where the movement is comprised of "S" curves, when the curves
hit the ground they push off and gain speed. There are also the side
winding method, used by the sidewinder in the deserts to keep as much
of its body off the hot sand as possible. The head is thrown forward while
the body uses the lateral undulatory method to push the snake forward.
The last style is called the concertina method and is used mostly by tree
dwelling snakes. It involves using the prehensile tail to tightly grip a tree
or branch while the head extends in search of a solid grip on another part
of the tree. Then the tail is pulled forward, and the process is begun all over again.

All known species of snake breed sexually. Most snakes lay eggs, though
some do bear live young. Some snakes protect their eggs and keep their
temperature regulated by wrapping themselves around them. Pythons are
well known for this, and King cobras will actually protect their nesting
sites by chasing away anything that comes too close!

Snake eyes are amazing things: they don't have eyelids, so they shed the
skin on their eyes as well as the skin on their bodies. When this happens,
damaged or scratched eyes are often repaired. Snakes have little use for
ears - they'd just get in the way or full of dirt, so the snake's ear is actually
internal and is connected to the lower jaw that is capable of of detecting
low frequency sounds ranging from 100 to 700 hertz. This inner ear also
allows snakes to detect motion, ststic position and sound waves travelling
through the ground. Oddly enough, a rattlesnake can't actually hear its
own warning rattle! The act of snake charming has nothing to do with the
music being played either. The swaying of the snake as it "dances" is
actually a defensive act in response to the movements of the person
playing the instrument.

Snakes have a renal protal system which allows blood to circulat through
the tail section of the animal before travelling through the kidneys and then
on to the head and heart. The snake's heart has only 3 chambers; mammals
have 4. The blood flows though the circulatory system which is similar to
our own, but while we have lymph nodes, snakes do not. They do have
a lymphatic system, however, so it can fight infection. They also don't
have a urinary bladder...they expel urea in a solid form, much the same
way a bird does. The white part of their spoor is the urea. Snakes do have
a gall bladder on their livers, similar to mammals.

Non-venemous snakes have 4 rows of upper teeth and only 2 rows are
attached to the lower jaw, one to each side of the mandible. Snakes use
their teeth for crasping, not chewing and are recurved so that once prey
is bitten the only direction it can move is toward the stomach.

Snakes mostly interpret their surroundings through taste by using their
tongues to detect tiny molecules of scent. An organ within their mouths,
the Jacobsen's organ, allows these chemicals to be read and interpreted
as to whether an object is prey or enemy, and how far away it is. The large
pits you see on the sides of a snake's head aren't nostrils; they're infrared
sensors which allow the snake to "see" potential prey by the body heat
they emit. Some snakes have such sensitive pits that they can detect
differences down to 0.002 degrees Fahrenheit!

Lizards

Sudanese Uromastyx, World's smallest chameleon from Madagascar, Australian Frilled Lizard and 2 Crested Geckos

Lizards, or Sauria, have 3751 known species in 16 families and 383 genera. Lizard skulls
are very different from those of snakes, however as snakes evolved from lizards, so there
are some similarities as well. For example, the bones of their skulls are only loosely held
together and the lower jaw is composed of 2 halves which come together at the front.
This restricts the size of the food they can eat, but it also enables them to chew in
some instances, such as when a Mali Uromastyx crunches his lentils, or when a bearded
dragon chomps crickets. Lizards are known as pleurodonts, meaning that teeth are
attached to the inside of their mouths but not to the jaws themselves. Of course, there
are a few exceptions to this rule. The rest of the skeleton is variable and, unlike snakes,
there are 4 functional appendages in most lizard species. Many species of lizard are
purely vegetarian, or herbavores, though some are meat eathers, and others still are
omnivorous, eating whatever happens by and can fit into their mouths.

Lizard skin is really quite unique and comes together to form scales. The margins where
these scales touch each other is called juxtaposed. They can be smooth or keeled, which
means they have a ridge on them. Other scales overlap and are called imbricate. Scales
serve many purposes: they protect the animal from predators, are used to identify species
from one another so mates can be found through sexual displays, and they also help
prevent water loss through the skin of the animal. It has only recently come to light
that the scales of some lizards actually help them collect and drink water! The horned
lizard from North America can actually drink water by dipping its hind foot into a small
puddle. The scales are situated in such a way that they suck the water up into the
channels between the scales and direct it toward the mouth where the lizard can then
lick it off its lips. This was demonstrated by a scientist to prove it could be done. Lizards
with this type of skin don't normally go dipping their feet in water to have a drink, but it
effectively served to show how, in the wild, the morning dew that collects on the lizard's
skin is wicked to its mouth in the same manner. Lizards can hear with the help of an
external ear opening similar to our own, though they don't have earlobes.

Lizards move in many different ways and come in all sorts of shapes and sizes. Several
species of lizards have no limbs at all and undulate from side to side like a snake. These
lizards can be differentiated from snakes because they have eyelids - snakes have none.
Other lizards have only vestigial front and/or back legs. Lizards have some of the most
incredibly adapted feet as well, from the Basilisk, also called Jesus Lizards, which can run
on water to the marine iguana with their webbed feet used for swimming, to the amazing
geckos who can climb even the smoothest glass with ease. Some reptiles, like some
monkeys, also use prehensile tails. The flying dragon from Asia has astounding feet that
spread out with huge webs between its toes. Although not capable of true flight, these
lizards can glide between trees like a flying squirrel!

Some lizard species reproduce sexually while others employ unisex cloning such as
whiptails and some desert species. Reports if this type of breeding also extend to
chameleons, night lizards, and geckos. No one really knows why or how this happens,
and the act of being able to breed by yourself is called "parthenogenesis".

Lizards can be a wacky looking bunch when they want to be! Adaptations which boggle
the mind include the chameleon's 360 degree independent eye movements, its long,
sticky tongue, and special hands and feet designed to grip branches firmly between
its stout fingers. A chameleon's tongue can extend the length of its body to snag lunch
on a neighboring branch! Some species of lizard can lose their tails and re-grow them,
though they never look quite as perfect as the original. This came about so that by
leaving a predator to munch away at its expendable tail, the rest of the lizard could
escape to safety. Some lizards use color changing chromatophors in their skin to blend
with their surroundings or to communicate with others of its species. A chameleon
will change color to suit its mood, showing one color when it's content and another,
more vibrant color to say "Stay away! I'm angry and I bite!"

Baby Leatherback turtle

The species Chelonians includes turtles, tortoises, and terrapins. For the most part, the
difference between a turtle and tortoise is is minimal - turtles live in or near the water
and have adapted to swimming by holding their breath underwater. They also have
flatter backs than tortoises. Tortoises live primarily in arid regions and are built for storing
their own water supply and walking on sandy ground. Tortoises occupy their own taxonomic
family, called testudinidae. All types of land and aquatic turtles come in a wide range of sizes,
colors, and shapes. Sometimes the name "terrapin" refers to those animals that fall somewhere
between a turtle and a tortoise, because they live in swampy areas.

Turtles, terrapins and tortoises are reptiles with a shell which encloses all of their internal organs.
They have been on our planet since the Triassic Period roughly 200 million years ago. This makes
them older than the great dinosaur groups! There are more then 250 species of turtle, the majority
of which live in tropical zones. Turtles have evoloved to inhabit just about any type of
terrestrial and aquatic environment. Freshwater turtles are found in rivers, lakes and ponds.
Marine turtles are found in just about every ocean and sea, and terrestrial turtles and
tortoises are found all over the world on all types of land; from damp and leafy rain forests
to drier, more arid regions. Some even live on both land and water, which means they are semiterrestrial.

The upper shell is called the carapace, and the lower is called the plastron and due to
adaptive changes and mode of life, their structures vary among different turtle
species. Some of the aquatic turtle species, the soft-shelled turtles, have their
carapace covered with leathery skin. Turtles come in all kinds of shapes and
sizes, ranging from species with a carapace with a diameter of only 6 inches
(15 cm) like the North American box turtle, to the huge Leatherback sea turtle
which can grow to a length of up to 8 feet or 2.4 meters! Some of the soft-shelled
turtles have a carapace which is covered in a soft, leathery skin, though most
turtle shells are hard and tough. Their carapace is actually attached directly to their
backbone, so the turtle can't slip in and out of its shell the way they show on cartoons
in television. Turtles also don't have a breast bone and have a three chambered
heart like those of other reptiles (except crocodilians).

From an anatomical stand point, turtles are divided into two basic groups: Cryptodira, which
lower their head below the spine and pull it straight back into the shell, and the side
necked turtles, or pleurodira who cannot withdraw their head in this manner. Rather,
t hey slip their head and neck sideways between the plastron and carapace, like
pulling your arm across your body. Turtles can often be seen sunning themselves on rocks,
logs and sandy beaches in order to regulate their body tmperatures as all reptiles must do.

All turtles, tortoises and terrapins must lay their eggs on land, and this is a huge task for
some of the species who are more at home in the water than on land. Sea turtles in
general are very slow and quite vulnerable on land because their flippers are specialized
to suit their aquatic environment. None-the-less, they are able to scoop out sand to
form a pit into which to lay their eggs. Tortoises typically lay 1-30 eggs per clutch,
and turtles can lay up to a few hundred per nesting site. The temperature at which
the eggs incubate determines the sex of the young within the shell, with males emerging
from slightly cooler eggs than females. Scientists aren't sure why this is.

Tortoises can live for an incredibly long time. The oldest tortoise ever recorded, almost
the oldest individual animal ever recorded, was Tu'i Malila, who was presented to the
Tongan royal family by the British explorer Captain Cook shortly after its birth in 1777.
Tui Malila remained in the care of the Tongan royal family until its death by natural
causes on May 19, 1965 at almost 188 years old. The Alipore Zoo in India was the
home to Adwaita, which zoo officials claimed was the oldest living animal until its
death on March 23, 2006. Adwaita (sometimes spelled with two d's) was an Aldabra
giant tortoise brought to India by Lord Wellesley who gifted it to the zoo in 1875 when
it was opened. Zoo officials state they have documentation showing that Adwaita
was at least 130 years old, but claim that he was over 250 years old (although this has
not been scientifically verified). Harriet, a resident at the Australia Zoo in Queensland
was thought to have been brought to England by Charles Darwin aboard the Beagle.
Harriet died on June 23, 2006, just shy of her 176th birthday!

Most land based tortoises are herbivores, grazing on grasses, weeds, leafy greens,
flowers, and some fruits and occasionally on insects and earthworms. Turtles and
terrapins eat what is available to them in their environments. Some eat grasses and
plants, others are carnivorous, some eat both. Sea turtles often include jellyfish and
other sea life in their diet! Unfortunately they also mistake floating bags and other
plastic items for jellyfish and end up eating these as well. The plastic often gets
lodged in the intestines or stomach, killing the animal. You can prevent this from
happening by disposing of plastic bags properly, recycling them,
or better yet, by using biodegradable or reusable bags.

Male tuatura from New Zealand

Tuaturas are often referred to as living fossils. They have remained almost unchanged
for roughly 220 million years. They have adapted to thrive in the often cool climate
of New Zealand, the only place on earth where it is found naturally. There are only
two known living species: the Spotted tuatura and the much rarer Brothers Island
tuatura; so named because it is confined to North Brother Island only. Both species
have spots however, the Brothers Island variety has olive brown skin with yellowish
patches while the other ranges in color from olive green to grey to dark pink and
brick red and are mottled with white spots. The Brothers species is also much smaller
than the spotted variety. The spotted tuatura is further divided into two
subspecies: the Cook Strait tuatura which lives on the other islands in and
around the Cook Strait, and the northern tuatura which lives on the Bay
of Plenty and some islands further north.

The skull of both species of tuatura is unique and is not at all similar to any other
reptile. The tip of the upper jaw is beak-like and separated from the remainder of
the jaw by a notch. There is a single row of teeth in the lower jaw and a double
row in the upper, with the bottom row fitting perfectly between the two upper
rows when the mouth is closed. Although most snakes have a double row of teeth
in their upper jaw, their arrangement and function is different from the tuatara's.
The tuatara's jaws, joined by ligaments, chew with backwards and forwards
movements combined with a shearing up and down action. The force of the bite
is strong enough to cut through chitin and bone. The tuatara's teeth are not
replaced since they are not separate structures like real teeth, but sharp
projections of the jawbone. As their teeth wear down, older tuatara have
to switch to softer prey such as earthworms, larvae, and slugs, and
eventually have to chew their food between smooth jaw bones.

Both eyes can focus independantly and use a special "duplex retina" that
contains two types of cells for seeing in bright and dim light and a tapetum
lucidum which reflects on the retina to enhance night vision. There is also a
third eyelid on each eye called the nictitating membrane that serves to
protect the eye from damage. What's really neat about the tuatura is that
it has a third eye on top of its head called the parietal eye! It has its own
lens, cornea and retina with rod-like structures and a degenerated nerve
connection to the brain. This eye is only visible on hatchlings when they
have a translucent patch on the top center of their skulls. This spot is
lost after the fourth to sixth month when it is covered by opaque scales and
pigment. The purpose of this eye is not fully known, though scientists believe
it may help in absorbing UV light to manufacture vitamin D as well as to determine
light/dark cycles and aid in thermoregulation. The parietal eye is part of the
pineal complex which, in tuatura, secretes melatonin at night. Melatonin is
known to assist in sleep.

The tuatura has primitive hearing organs, a trait it shares with turtles. They
have no eardrum and no ear hole. The middle ear is filled with loose, mostly
adipose tissue. Even though the hearing organs are poorly developed and primitive
with no visible external ears, they can still react to some sounds.

Adults are terrestrial and nocturnal though they emerge during the day to
bask in the sun and warm their bodies. Hatchlings are more diurnal. Tuatara
are capable of withstanding much cooler temperatures than most lizards but
they still hibernate during the coldest months of the year. They often live in
the abandoned petreo, prion and shearwater nesting burrows when they
can find them, or dig their own. The seabird feces attract the invertebrates
the lizards eat including beetles, crickets and spiders. They are also happy
to snack on frogs, other lizards (sometimes being cannibalistic), bird's eggs and chicks.

Tuarturas reproduce very slowly and take 10 years to reach maturity. Females
mate and lay eggs only once every four years. Tuatara eggs have a soft,
parchment-like shell. It takes the females between one and three years to
provide eggs with yolk, and up to seven months to form the shell. It then takes
between 12 and 15 months from copulation to hatching. This means reproduction
occurs at 2 to 5 year intervals, the slowest in any reptile. They also have the
slowest growth rate of any reptile, continuing to grow for the first 35 years of
their lives! The average wild specimen lives roughly 60 years, but in captivity
they have been known to live to be well over 100 years of age.

Crocodilia

Alligator, pygmy crocodile, and gharial

The order crocodilia is made up of large reptiles that appeared asbout 84 million years ago
in the late Cretaceous period. They are actually the closest living reatives to birds and
includes alligators, crocodiles, gharials and caimans.

Alligator "high walking"

The smallest species of crocodilian is the Cuvier's dwarf caiman and the largest is the
saltwater crocodile. Crocodilians have a flexible splayed stance and posture. They can
walk in a low, sprawled "belly walk," or hold their legs more directly underneath them
to "high walk." The semi-erect posture makes it possible for some species to gallop
on land if necessary and some species can reach speeds of over 10 km or 16 miles/hr!

Crocodiles replace their teeth throughout their lives and jouveniles replace teeth at a
rate of up to one new tooth per socket each month! As the animal ages, though, the
rate of tooth replacement drops until, in extreme old age, the animal no longer replaces
any at all. Each tooth is hollow, with the new growing inside the old, ready to replace
it should the first tooth be lost. The average crocodilian can go through 3000 teeth
or more in its lifetime! Crocodilians have a secondary bony palate that allows them to
breathe when partially submerged, even if their mouth is full of water. Crocodiles and
gharials have modified salivary glands on their tongues which are used to excrete excess
salt ions from their body. They are often seen lying with their mouths open, a behavior
called gaping. One of its functions is probably to cool them down, but since they also
do this at night and when it is raining, it is possible that gaping is also social,
indicating that the animal is relaxed.