Lizards are a group of reptiles
that are found all over the world, and live on every continent except for
Antarctica. They come in a wide range of sizes, from just over a centimeter to more
than 10 feet or 3 meters in length. Some lizard species are also noted for
peculiar adaptations and abilities. Lizards appear in a variety of shapes and colors, and have adapted to survive in a
wide mix of habitats, from deserts, forests, grasslands, jungles, and coastlines.
Some species of lizards are even kept as pets. Whatever the type, lizards are fascinating
creatures with their own place in the world. You're watching FreeSchool! There are over 6,000 species of lizards on earth,
including well known types such as chameleons, iguanas, and geckos. Like most reptiles,
lizards are usually cold-blooded, and rely on the environment around them
to regulate their body temperature. With four strong legs tipped with claws, scaled
skin, and a tail, lizards are easy to pick out.
As reptiles, most lizards lay eggs, although
as many as twenty percent of lizard species may give birth to live young. Unlike the eggs of
birds, lizard eggs have flexible, leathery shells. These soft shells lose more
water than birds' eggs, and so the mother lizard will lay her eggs
somewhere moist to prevent them from drying out. It can take anywhere from a few weeks to 18 months
for lizard eggs to hatch, depending on species, and while some species of lizards will guard
their eggs, others will abandon them as soon as they are laid. For these lizards, when the
hatchlings emerge, they are on their own.
Lizards are generally carnivorous, typically
feeding on insects and small animals, but many are also opportunistic eaters, meaning
they will eat whatever food is available to them. One lizard that is the exception
to this rule is the iguana. Iguanas are large lizards native to Central and
South America. Some specimens have achieved sizes of more than 6 feet or 2 meters, with
weights above 20 pounds or 9 kilograms. There are 35 different species of iguana,
and they can come in many different colors such as blue, yellow, pink, red, and
brown, but the common iguana is green. Unlike many other lizard species, iguanas are
mainly herbivores. Well suited to climbing, they spend much of their lives in trees,
where they have easy access to vegetation. Iguanas in the wild survive almost entirely on the
leaves of trees and vines, as well as fruits and flowers. Due to their plant based diet and gentle
nature, iguanas are sometimes kept as pets.
Now let's move on to a lizard that would
make a terrible pet: the komodo dragon. Komodo dragons are the largest living species
of lizard in the world, found exclusively on a few islands in Indonesia. These massive reptiles
can grow up to 10 feet or 3 meters long and weigh over 150 pounds or 70 kilograms, making them a
formidable presence in their native habitat. Unlike iguanas, Komodo dragons are carnivores.
Young dragons will hunt snakes, insects, and birds, but by the time a komodo dragon reaches
about a meter in length, their menu changes. They are known to hunt and kill larger prey,
including deer, pigs, and even water buffalo, but they also have a taste for carrion,
or the remains of dead animals. The bite of a komodo dragon is only a fraction
of the strength of something like a crocodile, but they have another advantage: venom.
Scientists believe that the venom in a komodo
dragon's bite may prevent wounds from healing, so that when they attack prey too
large for them to kill outright, it will gradually die after its escape, leaving
these giant lizards with a snack for later. But not all lizards can depend on size,
strength, and a mouthful of venom. Some lizards... have to be more clever. Chameleons are a group of lizards native to
Africa, Madagascar, and parts of Europe and Asia. They are best known for their ability to
change the color of their skin to blend in with their surroundings, but that is
far from the only trick up their sleeve. Like the komodo dragon, chameleons are carnivores,
eating mostly insects and other small animals. With such small, fast-moving prey, they
use a strategy for catching dinner that they share with frogs: they capture
it with their long, sticky tongue. The tongue of a chameleon is typically
about twice as long as its body, and is equipped with a sticky tip that adheres to
the prey. When the chameleon extends its tongue, it shoots out at high speed, allowing it to snatch
insects and other small prey in an instant. They locate their lunch with eyes
that are unique in the animal kingdom. These large, protruding eyes give
chameleons 360 degree vision, allowing them to look in any direction they
wish - or two different ones at the same time. Once they find something tasty, they can focus
on it with both eyes to get a better look. Unlike humans or other lizards, chameleons do not
have two eyelids that they can close. Instead, they have only one, shaped like a cone, with a
small opening to allow light to reach the pupil. Their peculiar eyelids mean that chameleons
cannot blink, although they do have a thin membrane that they can use to like an extra
eyelid to clean and moisturize their eyes.
Whether they are large or small, lizards play important roles in
the ecosystems in which they live. Lizards are both predators and prey. They help to
control the populations of insects and other small animals, and they are an important food source
for larger predators, such as birds and snakes. Despite their widespread distribution and
importance in the ecosystem, lizards face many challenges. Habitat loss, climate change, and
human interference are all threats to lizards, with many species being endangered or threatened. Conservation efforts are underway
to protect them and their habitats. It is important for us to understand
and appreciate the value of lizards in the natural world, and to work to protect
these fascinating and diverse animals.
