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

 

Lizard Land — Part 1 of 2

Land Iguana, Galapagos Islands

 

Marine Iguana, Galapagos Islands

Lizards are one of the most diverse and remarkable creatures on this planet; there are 6,000 species living on all the continents except Antarctica. Here are some of my favorites in this two-part series.

 

Although most lizards may seem vulnerable as fairly small, soft-sided creatures, they are hearty and flourishing survivors.

 

It is their antipredator adaptations that have rewarded lizards with success on the planet. Features such as camouflage, self-amputation, venom, and reflex bleeding aid these reptiles in numerous ways.

 

Camouflage. In the Hawaiian tropics, this gecko surprisingly blends into the lush tropical flowers and greenery. We were lucky to find this one on our rental car where it stood out.

 

Gold Dust Day Gecko, Hawaii

 

Here you see the Lobed Chameleon in Serengeti grass…barely noticeable in its camouflaged state. Imagine how many ferocious wild African species could eat this palm-sized chameleon…yet in Tanzania alone there are 100 species of chameleons.

Lobed Chameleon, Serengeti, Africa (in exact center of photo)

 

The chameleon, like many lizard species, changes color to hide from predators. They also have the ability to extend their long, sticky tongue to snap up insects without having to leave their hiding spot.

 

This frisky pair of spiny-tailed iguanas would have escaped our notice if they hadn’t been rustling in their chasing.

 

Spiny-tailed Iguana pair, Belize

 

We found a frill-necked lizard on every tree in this northern Australia eucalyptus forest. Invisible to us at first, the guide pointed them out.

Frill-necked Lizard, Atherton Tablelands, Australia

In addition to camouflaging, the frill-necked lizards have a unique scare tactic. Named for the ruff of skin around their neck, frill-necked lizards can expand their neck skin like the instant opening of an umbrella. They have bones in the frill that form rods extending their ruff, quickly transforming them to be bigger and more fierce.

 

This is a good BBC YouTube video of what the frill-necked lizard looks like when defending. 

 

Self-amputation. Another example of anti-predator adaptation is autotomy or self-amputation. Skinks and small lizards are known for their ability to escape from a predator by this method.

 

If a predator grabs onto their tail, they sacrifice it by ejecting it, and escape, leaving the predator with only a still-squiggling tail. Miraculously, they grow the tail back. It has been found that lizard DNA is responsible for regeneration, involving 326 genes.

 

You can see this lizard with its battle scars: a segmented tail, indicative of regrowth.

Green Anole, Costa Rica; segmented tail indicating regeneration

 

Venom. While most lizards are not harmful, there are a few who produce venom, like the Gila monster, Komodo dragon, and some monitors. Lizard venom has led to ongoing scientific research for medicinal drugs to help with blood clotting, weight loss, and diabetes.

 

Reflex Bleeding. Horned lizards have an antipredator adaptation called reflex bleeding. At least eight species of this lizard can squirt and aim a stream of blood from the corner of their eyes, shooting it a distance of up to five feet (1.5 m). The blood confuses the predator, and is also foul-tasting to dogs and cats.

 

Another extraordinary lizard characteristic is thermoregulation. As cold-blooded animals, they rely on the sun for supplying energy to move and function. For this reason, lizards can often be seen basking in the sun.

 

Marine Iguana colony, Galapagos Islands

 

Basilisk Lizard, Belize, Central America

 

Lastly, lizards vary incredibly in size and shape. This land iguana is one of the largest lizards in the world, weighing up to 25 pounds (11 kg) and measuring 3-5 feet long (0.9-1.5 m).

Land Iguana, Galapagos Islands

 

In contrast, this full adult gecko, aptly named the dwarf gecko, is half as big as a paperclip.

Dwarf Gecko, Belize

 

And finally, as an aficionado of wild lizards, I ask that if you ever seek to purchase a lizard for a pet, please be responsible in purchasing only lizards that are bred in captivity and legally bought and sold. Help keep our wild lizards wild.

 

Solar-generated animals that can change colors, regrow their tail, magically blend into their surroundings, and shoot blood. How incredible is that?

 

Written by Jet Eliot.

All photos in the wild, by Athena Alexander.

See you next Friday for Part 2 of Lizard Land. Thanks for joining me!

Western Fence Lizard, California

 

Lovable Lizards

Land Iguana, Isabela Isl., Galapagos

There are over 6,000 species of lizards on our planet, residing on all continents except Antarctica.  Here are some basic facts and photos of a few of my favorites.

 

One thing I love about lizards is their adaptability. Depending on the severity of danger, they can sacrifice their tail and grow a new one, change colors, and vanish in an instant.

Green Iguana, Costa Rica

Another thing I love is their solar power. Lizards are ectotherms, they require heat sources outside their body to function. Also known as cold-blooded (not technically accurate), lizards regulate their body temperature according to the sun.

 

Once in awhile I will find a lizard when the sun has been absent, like at dawn on a foggy day, and they are frozen in place. Immobile. I like this about lizards, too — their vulnerability. Of course, that’s not their favorite thing.

 

There are many remarkable features about lizards, read more here:

Lizard Wikipedia

 

Green Anole, Texas

 

Basilisk Lizard, Belize, Central America

With six thousand lizard species, there are thousands of variations. I have watched lizards run across water, eat algae under water, flare out their neck to twice its size, and hang upside down for days.

 

Some lizards change colors to attract mates, some change colors to escape detection (camouflage), and others are bright their whole life.

 

Hawaiian Gecko

 

Spiny-tailed Iguana pair, Belize

I live in a hot, dry climate in California. In the spring and summer we have three regular lizard species, each is a home-time favorite and much revered.

Western Fence Lizard, California

The western fence lizard is the most prevalent, we see them every day from May through October. The male does push-ups and displays a brilliant blue belly during breeding season.

Western Fence Lizard, California, gorging on nuptial ants

 

Plus, this lizard has an astonishing feature. They have a protein in their blood that kills the bacterium in the tick that causes Lyme’s Disease.

 

Ticks often feed on lizards’ blood, including the deer tick that carries Lyme’s Disease. When the deer tick feeds on the western fence lizard, the bacterium is killed. My chances of getting Lyme’s Disease are considerably less because of this  lizard.

 

We also have the alligator lizard, named for their resemblance to alligators. They are skittish and infrequent, but when they appear, it is a highlight of the day.

Northern Alligator Lizard, California

Our third reptile is the western skink. They are almost always hidden, their predator list is long. I’ve learned to recognize their sound when they rustle beneath leaves; so if I wait nearby, I sometimes see them.

 

Western skink, Calif.

 

Some lizards, like the skink, move like a snake. They have short legs and wiggle and slither. But most lizards are quadrupedal and move with an alternating gait. Another thing I love about lizards…watching them walk or run, a kind of reptilian sashay that says “attitude” to me.

Nile Monitor, Botswana

 

The marine iguana, the only underwater lizard in the world, lives on the Galapagos Islands. I’ve been snorkeling when they entered the water–that’s a strange thing, to be snorkeling with a large lizard. A true thrill. They sneeze out the sea salt when they return to land.

Marine Iguana, Galapagos

Lizards bask in the sun, leap through the air, let go of their tail if it’s in the jaws of a predator, and effortlessly change colors. I wouldn’t mind having all of these features, but since I cannot, I’m happy to watch…maybe I’ll learn something.

Written by Jet Eliot
Photos by Athena Alexander

 


Frill-necked lizard, Australia

 

Golden Tegu Lizard, Trinidad