Chameleon

Chameleons, or chamaeleons, are a special group of lizards known for their amazing ability to change colors. This helps them hide, or camouflage, in their surroundings. They belong to a family called Chamaeleonidae and there are about 200 different kinds, or species, of chameleons.

These lizards have many unique features. They have special feet that help them climb, tails they can grab with, and bodies that are flat on the sides. Some have crests or horns on their heads. Their eyes can move separately, which helps them see clearly when catching food.

Chameleons are mostly active during the day and eat insects, though the bigger ones can also catch small animals. Most live in trees, using their tails for balance, but some live on the ground. They are found in many places, mostly in Africa, with many species living only on the island of Madagascar. There are also a few in southern Europe, Asia as far as India and Sri Lanka, and some have been introduced to places like Hawaii and Florida.

Etymology

The word "chameleon" comes from ancient languages. It started from the Greek word khamailéōn, which means "lion of the ground." This Greek word was later borrowed into Latin as chamaeleōn. Over time, the English word "chameleon" was simplified from this Latin version.

Classification

Chameleons belong to a family called Chamaeleonidae, which was divided into two groups in 1986: Brookesiinae and Chamaeleoninae. Brookesiinae included small chameleons like Brookesia and Palleon, while Chamaeleoninae included larger ones such as Bradypodion and Chamaeleo.

Since then, scientists have debated these groups. By 2015, a researcher named Glaw updated the classification, placing only Brookesia and Palleon in Brookesiinae, with all other chameleons in Chamaeleoninae.

Change of colour

Further information: Animal coloration and Signaling theory

Some chameleons can change their skin colors. They can show many different colors such as pink, blue, red, orange, green, black, brown, yellow, and purple. This happens because their skin has special cells with tiny crystals that can change how light reflects off them.

Chameleons use color changes mainly to communicate with each other and to regulate their body temperature. They may show bright colors when they are being aggressive or darker colors when they are calm. Some chameleons can even change colors to better hide from specific predators, depending on what might be watching them.

Evolution

The oldest known chameleon is Anqingosaurus brevicephalus from the Middle Paleocene (about 58.7–61.7 mya) of China. Other ancient chameleon fossils have been found in the Czech Republic, Germany, and Kenya.

Scientists think chameleons may have lived much longer ago than these fossils show, possibly sharing a common ancestor with iguanids and agamids over 100 million years ago. Though many chameleons live in Madagascar today, they likely originated in mainland Africa, with some early migrations to the island.

Studies show that the way chameleons change color has evolved based on where they live. Chameleons in brighter areas tend to show brighter colors, while those in darker areas show colors that stand out more against their surroundings. This helps them communicate effectively with other chameleons.

Description

Chameleons are fascinating lizards that come in many sizes and shapes. The smallest known chameleon, Brookesia nana, is less than an inch long, while the largest, like Furcifer oustaleti, can be over two feet long. Many chameleons have unique features on their heads, such as horns or crests, and males often look very different from females.

Chameleons have special feet that help them climb trees. Their feet have five toes split into two groups, allowing them to grip branches tightly. They also have sharp claws for climbing. Some chameleons have spikes along their backs that help them hide by breaking up their shape.

Chameleons can see very well and can even see ultraviolet light. Their eyes move independently, giving them excellent vision in all directions. They catch insects by shooting out their long tongues incredibly fast to grab prey from a distance. Certain chameleons from Madagascar have bones that glow under ultraviolet light, possibly helping them communicate without affecting their color-changing abilities.

Distribution and habitat

Chameleons mainly live in sub-Saharan Africa and on the island of Madagascar. Some species are also found in northern Africa, southern Europe including Portugal, Spain, Italy, Greece, Cyprus, and Malta, the Middle East, southeast Pakistan, India, Sri Lanka, and islands in the western Indian Ocean. There are even introduced populations in Hawaii and Florida.

These lizards prefer tropical and subtropical areas, living in forests, woodlands, shrublands, savannas, and sometimes deserts. Most chameleons live in trees or bushes, but some spend time on the ground. Many chameleon species have small ranges and face threats mainly from habitat loss.

Reproduction

Most chameleons lay eggs, but some give birth to live babies. Eggs are laid a few weeks after the parents meet, and the mother digs a hole to put them in. Small chameleons may lay just a few eggs, while larger ones can lay many — up to 200 eggs at once! It can take several months for the eggs to hatch.

Some chameleons, like the Jackson's chameleon, give birth to live young after carrying them for about six months. Each baby chameleon is born inside a thin, clear sac and climbs away to start its own life soon after.

Diet

Chameleons mainly eat insects, but larger ones might also eat small lizards or young birds. For example, the veiled chameleon from Arabia eats crickets and leaves when water is scarce. Jackson's chameleon from Kenya and northern Tanzania eats a mix of small animals like ants and caterpillars, as well as plants like kale and berries. The common chameleon found in Europe, North Africa, and the Near East mostly eats wasps and mantises, and should have a varied diet including waxworms, earthworms, and green leaves. Some chameleons, like the panther chameleon from Madagascar, get vitamin D3 by sitting in the sunlight, which helps them make more of this important vitamin.

Anti-predator adaptations

Chameleons have many natural enemies, including birds, snakes, and even tiny creatures like ants that threaten their eggs and young. Because they can't usually run away, chameleons hide instead. They change their colors and patterns to blend into their surroundings or to break up their shape, making it hard for predators to see them.

If a chameleon is spotted, it will stand its ground. It might flatten its body to look bigger, open its mouth to warn an attacker, and if needed, use its feet and jaws to defend itself. Sometimes, it will also make noises as part of showing it means business.

Parasites

Chameleons can get sick from tiny creatures called parasites. One type is called nematodes, or roundworms, which can be spread by insects like ticks and mosquitoes. Another way these parasites get into chameleons is through food that has roundworm eggs.

Chameleons can also be affected by other parasites, such as protozoa. These include Plasmodium, which causes malaria, Trypanosoma, which causes sleeping sickness, and Leishmania, which causes leishmaniasis. They may also get parasites called coccidia.

As pets

Chameleons are popular pets, often brought in from countries like Madagascar, Tanzania, and Togo. Common types include the Senegal chameleon, the veiled chameleon, the panther chameleon, and Jackson's chameleon. These animals need special care and attention.

The United States has been a big importer of chameleons since the 1980s. Rules have changed to help protect wild chameleons, and some have become invasive in places like Florida. Despite this, chameleons remain popular pets, and many are now bred in the U.S. for sale.

Historical understandings

Ancient thinkers like Aristotle wrote about chameleons in his book History of Animals. Later, Pliny the Elder also talked about them in his Natural History, mentioning their ability to change colors to hide.

The chameleon appeared in books like Conrad Gessner's Historia animalium in 1563, and even in Shakespeare's Hamlet, where a character makes a joke about chameleons eating air, showing what people believed back then.