Lizard Land — Part 2 of 2

Green Iguana, Belize, native

 

Last week in Part 1 of this series we looked at lizards’ antipredator adaptations, camouflage, and size. Today we look at their skin, and various ways they move, sense, and communicate.

 

For starters, they are gloriously prehistoric. When you watch a lizard, especially the way it moves, it’s almost as if you are watching a dinosaur. The evolution of reptiles dates back 310-320 million years; more info here. 

 

Marine Iguana, Galapagos Islands

 

Blue-tongued Lizard pair, entwined, Sydney, Australia

 

Spiny-tailed Lizard, Ambergris Caye, Belize

 

Skin. Lizard skin is covered with overlapping scales made of keratin, providing protection from the environment. Scales also help prevent water loss, especially important in hot, dry deserts.

 

This photo shows the textured scales.

Western Fence Lizard, California

 

Tough and leathery, lizard skin is shed as the animal grows; they usually eat it for the minerals.

 

Locomotion.  Lizards live on the ground, in trees, rocks, underground, and even water. Therefore, they move in many different ways.

 

Although there are some legless lizards, most lizards are quadrupedal. Their gait has alternating movement of the right and left limbs, requiring the body to bend–shown in this photo of the Nile monitor.

 

Nile Monitor, Botswana, Africa

 

One of my favorite lizards for their movement is the common basilisk. When alarmed, basilisks rear up on their two hind legs and skitter across the water, earning them the name Jesus Christ Lizard. I’ve seen them run bipedally on the ground as well.

 

This photo demonstrates the basilisk’s muscular hind legs, necessary for bipedal locomotion.

 

Basilisk Lizard, Belize

 

Many species of lizards can effortlessly leap two and three times their body length. Lizards with short legs, like the skink, undulate like a snake.

 

Skink, California

 

Some lizards are extremely fast, while others, especially larger ones, are more languid. In addition, how much sun they have stored in their body is directly relational to speed.

 

The black spiny-tailed iguana (Ctenosaurus similis) is known as the fastest lizard, clocked at 21 mph (34 kph).

 

Black Spiny-tailed Iguana, Ambergris Caye, Belize

 

Geckos get the prize for hanging upside down. Their adhesive toe pads allow them to adhere to most surfaces.

 

The Asian House Gecko has the broadest distribution of any lizard in the world.

 

Asian House Gecko on the ceiling, Kakadu NP, Australia

 

Senses. With over 6,000 species of lizards, there are many variations of how lizards sense their environment–here are a few notable ways.

 

Eyes. Many lizard species, especially iguanas, have a parietal eye, a third eye, on the back of their head. It is photoreceptive and regulates circadian rhythm and hormone production for thermoregulation. Although it does not form images, it is sensitive to light and movement, helpful for detecting predators. The eye is difficult for us to see.

 

A chameleon can steer each eye in opposite directions. Geckos do not have eyelids, so they lick their eyes to keep them clean and moist. Geckos, like monitors, have acute vision.

 

Ears. Instead of external ears, lizards have ear holes or openings. The eardrums, or tympanic membranes, are just below the surface of the skin. These two close-ups clearly show the “ears.”

 

Dragon Lizard, Australia. Ear hole is reddish-brown circle below and left of eye.

 

 

This frill-necked lizard’s ear opening is just right of center photo, in an almost straight line below the eye. Australia.

 

Nose. All lizards, like snakes, have a specialized olfactory system for detecting pheromones or chemical signals. They have a vomeronasal organ (VNO), located in the soft tissue of the nasal septum. When you see a lizard sticking out its forked tongue, as in the photo below, what you are witnessing is the transferring of scent information from the tip of its forked tongue to the VNO.

 

Golden Tegu Lizard with forked tongue out, Trinidad

 

Mouth. Most lizards are predatory and hunt small invertebrates and/or insects. We have lizards to thank for keeping the insect population in check.

 

This western fence lizard had a fruitful day in my backyard. As winged nuptial ants were streaming from a rock fissure, he gorged for at least an hour.

 

Western Fence Lizard, California, eating nuptial ants. Notice all the dead winged ants he hasn’t yet had the chance to consume.

 

Here in California we are lucky to have the western fence lizard, because ticks that feed on this lizard do not spread Lyme disease. This lizard’s blood kills off the Lyme bacteria.

 

The marine iguana, found only in the Galapagos Islands, forages on algae, kelp and other marine plants. They will dive up to 98 feet (30 m), and can stay submerged for an hour.

 

While underwater, marine iguanas ingest salt. The salt is filtered from the blood and then nasally excreted. We saw many of them squirt salt out their nostrils.

 

This photo shows the marine iguana’s lovable face encrusted with algae (green) and dried salt (white) on it.

 

Marine Iguana, Galapagos Islands

 

As squamates, lizards have movable upper jaws, and some lizards, like the green iguana, have very sharp teeth capable of shredding leaves and even human skin. All lizards have teeth, dentition varies.

 

Communication. Lizards make sounds for courtship, territorial defense, and distress signals. Geckos are the most loquacious lizards, with chirps and squeaks that can be surprisingly loud. Sometimes you’ll hear a lizard hiss, a warning.

 

Other forms of communication include:  various body postures like push-ups and head-bobs, as well as the expansion of the dewlap. Tail-flicking is common in territorial disputes.

 

We found this dapper anole with a bright orange dewlap in a Texas swamp.

 

Green anole, Texas

 

This green iguana below, near a river in Costa Rica where it is native, was nearly five feet long (1.5 m) including the tail. An arboreal lizard, they hunt and bask in the trees and can easily break a fall with their hind legs.

 

This photo shows his crescent-shaped, uninflated dewlap under the neck. Dewlaps are muscle-controlled, and help regulate body temperature; also used in courtship and territorial displays.

 

Green Iguana, Costa Rica

 

Leaping Lizards Batman! They are the coolest animal on this planet!

Thanks for joining me in Lizard Land.

 

Written by Jet Eliot.

All photos in the wild, by Athena Alexander.

 

Great Basin Fence Lizard, Great Basin NP, Nevada