Habits and activities of lizards

These animals raise many questions: how does a lizard's tail come off? How does a chameleon change its color? How can a flying dragon glide? When we studied the topic “reptiles” as a class, I found answers to some questions, but not all. And I decided to get to know the reptiles better and find out more about them. That's why I chose this topic for the project.

With more than 3,500 species, the lizard suborder is today the largest group of reptiles. Lizards come in a variety of sizes, from the 2.5-centimeter gecko to the 3-meter giant Komodo dragon, appearance and coloring.

Sensitive tongue

To understand what is happening around, lizards stick out their tongues. This way they find out where their relatives, probable prey or enemies are. But this is not the only purpose the lizard uses for its tongue.

In the world of reptiles, the arboreal chameleon is rightfully considered the most accurate shooter. Its tongue, curled in its mouth, is the same length as its body, or even longer. Having discovered an insect, the chameleon “shoots” its tongue and immediately eats its prey. To intimidate enemies, the Australian giant smooth lizard (blue-tongued skink) sticks out its tongue and waves it threateningly. Geckos wash themselves with their tongue and even rub their eyes with it.

Masters of Disguise

Many lizards change color, this is well known. In order to avoid being noticed by both future victims and predators, they disguise themselves as their environment. And first place for the ability to change its color should rightfully be awarded to the chameleon, which does this depending on its mood.

Eggs and babies

Lizards, like snakes, are ovoviviparous. But in most species, the mother lays eggs and immediately leaves. The female leopard gecko lays her eggs in a shallow nest. During the months during which the embryos develop inside the eggs, the soft and sticky shell of the egg will become hard and durable.

The baby green iguana's mother left a long time ago, but once it emerges from the egg, it will be able to take care of itself.

The female North American striped skink (Japanese skink) is one of the few lizards that guards its eggs and cares for its young until they can survive on their own.

Voidtooth

The poisonous serpentine is too clumsy to chase prey, so it feeds on eggs and newly born animal cubs. It stores excess nutrients in the tail in the form of fat and, as a result, can eat nothing for more than a year.

Marine Iguana

The marine iguana, which lives on the Galapagos Islands (they are located almost 1000 kilometers from the coast of South America), is the only lizard that has adapted to life in sea water. For large seaweed - its favorite delicacy - the marine iguana can dive to a depth of 9 meters. Coming out of the cold water, she climbs onto the rocks and basks in the hot sun.

Frilled lizard

The Australian frilled lizard spends most of its life in trees. When she has to go down to the ground, she stands up almost vertically on her hind legs, opens the huge collar that frames her head, opens her mouth and runs away with a hiss.

Water Runner

The basilisk, which lives in Central and South America, can actually run on water. Having developed incredible speed, this lizard manages to take several long steps with its long legs before its body plunges into the water. A sail-like crest runs along the entire body of the helmeted basilisks.

Once mistakenly classified as a lizard, the hatteria is actually the only surviving representative of a separate group of ancient reptiles. The New Zealand Maori gave the tuatteria a name that means “bearing thorns on its back.”

The skull of the tuateria is very durable and similar to the skull of a crocodile. The hatteria shares its home with seabirds and spends the hottest part of the day there, crawling out of its burrow to hunt at night. Unlike other reptiles, it can lead an active lifestyle at fairly low air temperatures. At the beginning of life, tuataria develop slowly. Their young hatch from eggs after 12-15 months, in this sense, tuataria are champions among reptiles. And they also live a long time - usually more than 100 years. One of the most interesting features of the hatteria is their third eye, located at the top of the brain. It is sensitive to light, although it is covered with skin on top, but, unlike real ones, it does not see anything.

Barbed protection

Toad-shaped, or horned, lizards are small animals with a toad-like head. Their bodies are covered with small spiky spines and very sharp teeth. If the toad lizard is very frightened, it may release streams of blood from the corners of its eyes.

Giant lizard

The weight of the largest lizard - the giant Komodo dragon - reaches 160 kilograms. He hunts large animals - deer and wild boar. Sometimes monitor lizards even attacked people and killed them. Komodo dragons live only on small Indonesian islands.

Viviparous

Where did this name come from? The fact is that lizards, like other reptiles, lay an already fertilized egg; it is to some extent protected from adverse environmental influences. But even an egg with a thick shell requires careful handling. It can develop successfully only at a certain temperature and humidity, being protected from mechanical damage. It is not surprising that some reptiles have found a way out in viviparity.

In different species one can find different stages of the transition from the actual laying of eggs to true viviparity. Females of many species lay eggs in which the embryo has already begun to develop. Sometimes the development of the embryo in newly laid eggs reaches such a level that the incubation period of the eggs is significantly reduced and the young hatch soon after the eggs are laid. In some lizards, almost all the development of embryos in eggs occurs in the body of the female, and she no longer lays the eggs themselves, but live young, but still in the egg shell. Newborns immediately destroy these shells and begin to lead an independent life. This phenomenon is called ovoviviparity. Our viviparous lizard belongs to such ovoviviparous species. Viviparity is an adaptation to harsh cold environmental conditions. This is understandable: the cold soil of the northern regions is not very suitable for incubating eggs. The same viviparous lizard lays eggs in the southwest of its range, in the Pyrenees, in a drier and milder climate.

WITHOUT MALES

Lizards have occupied a very important place in scientific research. For example, while studying lizards, scientists discovered the phenomenon of natural parthenogenesis among terrestrial vertebrates. What is parthenogenesis and why was its discovery in lizards revolutionary? Parthenogenesis is reproduction without the participation of males and is a fairly widespread phenomenon in the animal world. There are many known species of animal worms, mollusks, insects, crustaceans and other invertebrates that reproduce normally without the participation of males, and often they do not have a male sex. As for highly organized vertebrates, it was believed for a long time that same-sex reproduction was impossible in them.

HOW THE TAIL COME OFF

Most people's knowledge about lizards is very poor. The most well-known fact is, perhaps, that lizards can throw off their tail when in danger - a very interesting phenomenon called autotomy. In the caudal vertebrae of lizards capable of autotomy, there are non-ossifying layers along which the tail breaks off. The breaking itself occurs due to a sharp contraction of the tail muscles. The discarded tail wriggles intensely for a long time, distracting the predator from the lizard itself, which meanwhile manages to hide. The base of the discarded tail hardly bleeds - the torn vessels are reflexively compressed by the muscles. And soon a fairly rapid process of growing a new tail begins, almost indistinguishable from the old one, and the vertebrae are not restored, but are replaced by a cartilaginous rod, which is why a new separation is possible only higher than the previous one. A restored (regenerated) tail is usually easily recognized by its slightly different scales, and often also by the color of the regenerated part. By the way, autotomy is not a voluntary, but a reflex act: if you carefully glue a living lizard by the tail, it will not be able to throw away part of the tail and thereby free itself. However, not all lizards can cast their tails. Those of them whose tail plays a special role (an oar, an organ of attachment or protection) are deprived of both the ability of autotomy and regeneration.

They are trying to instill the abilities of a lizard in a person

Regrow severed limbs, quickly and without a trace heal deep wounds, restore damaged organs - all this can be done by some amphibians and reptiles, but the human body is not capable of doing this. British scientists will have to find out whether it is possible to give him the same abilities. Among amphibians and reptiles, there are many creatures that have the ability to “repair” themselves. Lizards, when attacked by a predator, can get rid of their tail, and then grow it back in 3-4 months. Salamanders are able to regrow damaged limbs, restore parts of organs and even the brain.

Enrique Amaya, a tissue specialist at the University of Manchester, talks about his experiment: “We cut the tadpole. It was a large wound, equivalent to what a 20-year-old man would get from falling off a motorcycle at 100 km/h. Within an hour and a half it was completely healed.” However, the scientist notes, grown frogs lose this ability.

Recently, the British charitable Healing Foundation donated £10 million to scientists at the University of Manchester to help them unravel the phenomenon of organ and tissue regeneration. Researchers must identify the genes responsible for recovery and figure out how they control such a complex process, and then try to instill these abilities in humans. This work began a long time ago: Professor Amaya identified 10 thousand genes in the frog that are responsible for regeneration, some of which were similar to human ones. “Don't think this goal is unrealistic,” Amaya says. - The potential for regeneration is in each of us. Human fetuses in the womb, if operated upon before the sixth month of pregnancy, heal wounds without leaving scars, but this ability is subsequently lost. Humans and amphibians share 85% of their genes, and it is very likely that the adult human has latent genes for scar-free healing.” The salamander regenerates organs thanks to the blastema, a universal group of cells that have the ability to transform into any tissue. Mammals, whose brain and body structures are much more complex, have lost the ability to regenerate. Stem cells, from which all organs are “built,” almost immediately after birth lose their universalism and acquire specialization. Research from the University of Manchester will explore whether the salamander's regeneration mechanism can be applied to an adult frog, then try to transfer the method to mice and then to humans. Scientists hope in the future to develop drugs or gene therapy techniques that can restore human limbs that are damaged or completely lost in accidents. “Already in this generation, a new method for restoring human limbs, organs and skin will become possible,” promises Professor Amaya. "It's a question of money, resources and research," says Gus McGruther, who leads research into plastic and reconstructive surgery at the University of Manchester. But this will certainly happen." The problem that doctors must solve when developing a new method is how to avoid uncontrolled cell division during regeneration, which leads to cancer.

I went to the dacha with my parents for the weekend. There I found two places where there are a lot of lizards, and I took into account the fact that they bask in the sun in the spring. The first place was behind the house, there was firewood there, and the second was in an old stump. There were about 7-8 lizards in the stump. Where the firewood lay, the lizards were very fast, I could not keep up with their agility. I was just trying to catch the lizard when it ran away. They reacted to my shadow and felt the approach of my hands. But I was able to outwit them: I took a thin stick, pressed the lizard, and then quickly grabbed it with my hands near the head, because I knew that it could bite. So I caught five lizards. They were all from a stump. I couldn't catch a single one in the firewood. They were very fast, and their color blended with the wood. These were tree lizards. One of the lizards' tail came off, it twisted and flew to the side. In the place where the tail was, a depression formed, there was no blood, and at the edge of the tail there was a protrusion, also without blood. But I was still able to catch this lizard without a tail. I collected the lizards in a jar, in the lid of which I made holes so that air could flow in. I also saw two lizards fighting. The larger lizard delivered three bites and the smaller lizard began to bleed. I didn’t see the end of the battle; they ran away, but then I found the head of a lizard near a tree stump. I don't know for sure whether it was the same lizard.

I left two lizards in the jar to watch them, and I released the rest. After ten days of living in the jar, the tailless lizard developed a small tail. Both lizards eat grass, live quietly, calmly, and do not fight. They are inactive in the bank. As soon as the lizard develops a full-fledged tail, I will release them. I'm interested to know how long it will take for this to happen.