Interesting Lizard Facts
Dr. Nancy Anderson
With so many different lizards in the world, we are just beginning to understand them. Here are a few facts about these fascinating animals that will amaze and delight your friends (and may even prove useful during game shows). Many lizards (but not monitors or chameleons) can undergo tail autotomy; in other words, they can lose the tail to distract or escape from a predator. The tail breaks through a predetermined fracture plane in a vertebra. It will grow back, but without bone (just a rod of cartilage), and will be slimmer, shorter and a different color, with small scales.
Some skinks and geckos, such as the tokay, have eyelids. But like snakes, the two lids have fused to form a clear "spectacle," which sheds along with the rest of the skin. The leopard gecko has more traditional eyelids.
How can you tell that a legless lizard is not a snake? He has eyelids and you can see an opening for his ears.
Like snakes, lizards have a Jacobsen's organ, and they smell by "tasting" the air. When lizards flutter the underside of their throats they are moving air past the Jacobsen's organ.
The Gila monster (Heloderma sucpectum) and the Mexican beaded lizard (Heloderma horridum) are the only two venomous lizards.
The Komodo dragon is the largest lizard, reaching 10 feet. These are clever hunters; once they know their prey's travel routes, they will wait to ambush them. Having bitten a large animal on the leg, instead of killing it immediately, the Komodo will allow the toxins produced by bacteria in the wound to weaken the animal over several days. The dragons track their prey, waiting until the animal is too weak to escape.
Most lizards replace their teeth throughout life, with the exception of the chameleon and the Agamid lizards.
Some horned lizards (Phrynosoma sp.) can squirt blood from their eyes. By constricting muscles, which prevents the flow of blood out of the head, blood pressure builds in the head until vessels in the inner corner of the eyes rupture, squirting blood up to 4 feet.
The "third" or parietal eye seen on the top of the head of lizards (such as the green iguana) contains a lens and retina-like structure, which connects via nerves to the pineal gland in the brain. Although it does not form images, this structure is important in governing hormone production related to time spent basking.
Herbivorous lizards such as the green iguana can conserve water by excreting excess salt from the blood stream through a nasal "salt gland." This is what produces the crusty white substance often sneezed out by iguanas.
Unlike other lizards, geckos have vocal cords, which allow them to vocalize.
The basilisk and the collared lizard (Crotaphytus collaris) are capable of bipedal locomotion (they can run on their hind legs). When young, they can even run on water.
Flying or draco lizards, found in India, soar between trees using wing-like membranes linking their front and rear legs. They come to the ground only to mate and to lay their eggs.
Records for lizard longevity may be held by a Mexican beaded lizard (33 years 11 months) and a Cayman Island ground iguana (33 years 5 months).
Do geckos have suction cups on their toes? No. Thousands of fine, densely packed hair-like structures on the underside of the toes of most gecko species allow them to defy gravity by gripping the microscopic irregularities in apparently smooth vertical surfaces, such as aquarium walls. Ground dwelling leopard geckos lack these little hairs and have claws instead.
Pigment filled cells, called chromatophores, are located in the skin of the chameleon. These cells expand and contract, in response to the color of the environment and the need for concealment, as well as to the animal's psychological or physical state (e.g. pain or aggression).