What is the name of a lizard that runs on water? Reptiles running on their hind legs remains a mystery
The basilisk can run through water up to 400 meters at a speed of 12 km/h.
Helmeted Basilisk - tree lizard, living in humid tropical forests. Distinctive feature Basilisk is the ability to run on water, holding its body on the surface with rapidly alternating blows hind legs.
Your name helmed basilisk received due to its resemblance to the mythical creature basilisk, which had a red crest on its head resembling a crown.
Because of its ability to walk on water, Costa Ricans call the helmet-bearing basilisk Jesus Christ.
The crest on the head of males is much larger than that of females. Average length The lizard is 50 cm and weighs 200-600 g. They are excellent swimmers, able to stay underwater for up to 30 minutes.
They help the lizard stay on the surface of the water when running. frequent blows paws that do not have swimming membranes. As a result of rapid shocks, holes with walls appear in the water, which behave as if they were solid during the time between two shocks. Starting from back wall With high speed, the basilisk does not submerge in water.
According to measurements by scientists from Harvard University, a full step of a basilisk on the water surface lasts 0.068 seconds, and the repulsion time is 0.008 seconds.
Relying only on its hind legs, the basilisk is capable of running quickly on land, reaching speeds of up to 11 km/h. While running, he flies some distance through the air.
A person weighing 80 kilograms can only move as fast if he reaches a speed of 500 kilometers per hour.
The life expectancy of this reptile in captivity does not exceed 10 years.
Helmeted basilisks are omnivorous and unpretentious. They feed on plants, vegetables, insects, snails and small frogs. And basilisks are hunted by larger reptiles, predator birds and fish.
Basilisk is not so much a scientific term as a literary one. In the era of the Dark Middle Ages this was called fantastic creature with the head of a rooster, the body of a toad and the tail of a snake. But it turns out that in nature there is a real reptile with this name and it can do some “magic”. What kind of animal is this?
Double-crested basilisk (Basiliscus plumifrons).
Biologists refer to basilisks as 4 species large lizards, reaching a length of 1.4-2 m. True, 70% of their body length falls on a thin tail, therefore, despite big size, basilisks are quite light and defenseless. Like their related iguanas, they have a crest on their backs, but these reptiles owe their name not to it, but to the leathery decorations on their heads. Obviously, because of the similarity of these formations to a cock’s comb, they were named after the mythical monster. Another physique feature is long fingers on hind legs. Sometimes it seems that they prevent the basilisks from moving, but in fact the opposite is true.
This piercing gaze also belongs to the basilisk. All species of these lizards have eyes yellow color- another feature that gives them a resemblance to a dragon.
All 4 species of these lizards live in northern South America, throughout Central America and in southern Mexico. Recently, basilisks arrived in Florida and learned to tolerate colder temperatures here by hiding in the forest floor. They inhabit only damp forests and dense thickets along the banks of reservoirs. Usually these lizards sit on the lower branches of trees and roots protruding from the water.
A male double-crested basilisk at rest.
But as soon as danger appears, they instantly take to their heels, and depending on the location of the animal, two defense strategies are used. If it is far from the water, then the basilisk quickly buries itself in the sand or litter, and to prevent sand from getting into its nose, the lizard’s nostrils close with special valves. In this position, he is able to remain motionless for a long time. If a body of water is nearby, then the basilisk rushes headlong into the water and runs as hard as it can... along its surface! This may seem like a fiction, but all individuals without exception have the ability to move on the surface of the water without drowning, and these are the only animals in the world that can move like this! By the way, the basilisk runs through the water like a dragon, that is, exclusively on its hind legs, which is also quite unusual for reptiles. We can say that walking on water is as easy for these animals as it is for us to walk down the street. For this they are sometimes called “Jesus lizards,” because it was Christ who first demonstrated such a miracle. But if the Bible explains the miracle of Christ by the presence of God's power, then what helps the basilisks run?
Basilisk demonstrates the miracle of walking on water.
In fact, the secret of unsinkability is quite simple. The long toes of the hind legs distribute the weight of the animal over a larger area; in addition, when running, the scales on the toes protrude, which makes running easier. In addition, the basilisk thrashes its paws so quickly that it simply does not have time to drown (the speed reaches 1.5 m/s). However, this method of movement requires a lot of energy, so the lizard only has enough strength to run 3-4 m, after which it plunges into the water and then swims as if nothing had happened. Since young individuals weigh less than older ones, their running distance is somewhat longer - 10-20 m. Obviously, the biological meaning of this behavior is to make a saving throw and at a critical moment to distance themselves as much as possible from the enemy.
British scientists have tried to shed light on the reason for the bipedal movement of some lizards. The results of the new study did not fully confirm any of the main theories and suggest that reptiles stand on their hind legs either by accident or due to some unexplained advantage.
A report on this work was published in the Journal of Experimental Biology.
No one knows exactly why some species of lizards periodically walk on two legs. Back in the middle of the last century, American zoologist Richard Snyder from the University of Washington suggested that this allows them to run faster and be more resilient.
Another hypothesis, proposed in 2003 by Peter Aerts from the University of Antwerp, argued that bipedal locomotion is not an independent adaptation of animals. On the contrary, it may be a by-product of another evolutionary process– changes in body structure and shift of the center of gravity back.
According to the Belgian scientist, as the morphology of some lizard species changed, they began to periodically stand on their hind legs after reaching a certain acceleration. Like sea boats, For example.
Comparative physiologist Christopher Clemente from the University of Cambridge and his colleagues decided to put both theories to the test.
Lizards of this species feed on insects, and their length varies from 20 centimeters to a meter. Along with the tail (photo from ribbitphotography.com).
Scientists captured 16 individuals of the Australian bearded dragon. Each reptile was released on treadmill and measured how much of the way she moves traditional way, and which one is on two legs. In four individuals, the overall speed and resulting accelerations were additionally measured.
After making adjustments (and based on the actual size of each individual), the researchers found that running on their hind legs did not increase the endurance of those lizards that resorted to it - on the contrary, their runs were shorter. Moreover, the speed did not increase with this method of movement either.
The adaptation hypothesis was thus not confirmed. Dr. Aerts' model generally agreed with the observational results, but also turned out to be inaccurate.
Although it made it possible to guess which lizards should be the first to stand on their hind legs, full compliance with the calculations was not observed: three out of four individuals got up from the ground before they reached the acceleration necessary to compensate for the shift in the center of gravity.
“For many lizards, bipedalism does seem random,” says Dr. Clemente. “Even in the absence of contact of the forelimbs with the ground, the mechanics of their movements do not change.”
At the same time, the British biologist adds that there must still be some advantage provided by “getting off the ground.” But if this separation does not occur to increase endurance or speed, then for what?
"Perhaps two legs are less likely to be damaged in the process individual development individuals,” Christopher suggests.
But skeptics cite his own results as a counterargument. They believe that the data obtained should force scientists to henceforth refrain from making unfounded assumptions.
“Many adhered to the rather controversial practice of putting forward a wide variety of hypotheses about the meaning of certain species characteristics in an animal only on the basis of its appearance. Real, full-scale research tends to dispel such fictional stories, says evolutionary biologist Thomas Roberts (
Lizard Run Sauripes hadongensis from pterosaur Pteraichnus koreanensis. Reconstruction following the footsteps.
Lizards may have walked on their hind legs about 110 million years ago, according to South Korean, Chinese and American paleontologists, who described the oldest known lizard tracks in a paper published in Scientific Reports.
Some modern species, including the frilled lizard ( Chlamydosaurus kingii) and zebra-tailed iguana ( Callisaurus draconoides) in case of danger they run away on their hind legs. And the helmet-bearing basilisk ( Basiliscus basiliscus) moves on two legs and on the surface of the water. This way the lizard can develop greater speed than on four legs.
Since the center of gravity of lizards is closer to the back of the body, when moving they can stand on their hind legs and move only on them. With this method of locomotion, the tail is critical. Researchers, figuring out whether it helps two legs run, cut off half of the basilisks' tail. After this, the reptiles lost the ability to move on their hind legs. Lizards also benefit from short forelimbs, which do not weigh down the front part of the body.
In the process of evolution, locomotion on two legs (bipedalism) appeared twice in reptiles: in Triassic(251-201 million years ago) in archosaurs (a group that includes dinosaurs, birds and crocodiles), and a second time in lizards, it is unknown in what period. Paleontologists find the remains of ancient lizards quite rarely, and traces were found only three times, all younger than 65 million years.
The authors of the new study, led by Hang-Jae Lee from the Institute of Geosciences and mineral resources The Koreans described fossils in which four tracks of tracks with 29 paw prints were perfectly preserved. Traces were found in the Haman sediments in South Korea, which date back to 125-100 million years ago. Paleontologists suggested that they were left by a reptile from the infraorder Iguanaidae, and identified it as an ichnogenus and an ichnospecies (this is the name given to taxa described by traces) Sauripes hadongensis.
Fossil Photography and Footprint Drawing Sauripes hadongensis
Based on the morphology of modern lizards, the researchers hypothesized that most of the tracks (25 out of 29) were made by the hind legs, with longer toes. Judging by the depth of the prints, the reptile ran with its paw on its toes, and not on its entire foot. In two chains of tracks, the distance between them, already considerable, increased. This indicated that the lizard was gradually picking up speed.
Enlarged photographs of (a) front and (b) hind paw prints Sauripes hadongensis
Hang-Jae Lee et al./Scientific Reports, 2018
The researchers noted that in the Haman sediments, fossilized traces of a pterosaur were found in the same layer Pteraichnus koreanensis. Some of these flying reptiles fed on small land animals and carrion. Therefore, it is likely that the predator could hunt Sauripes hadongensis, and they, running away from danger, stood on two legs.
Previously, lizards helped researchers hypothesize the existence of a land bridge between India and Asia 50-55 million years ago, 25-30 million years before the subcontinent collided with Eurasia. Phylogenetic analysis showed that lizards moved from Asia to India at least twice.
Ekaterina RusakovaMany people believe that the "basilisk" is literary term, because in the Middle Ages they called it that fantastic monsters with a toad's body, a rooster's head and a snake's tail. But, as it turned out, this term also has scientific significance, since in nature there are reptiles with the same name. What kind of unusual animal is this?
Features of the appearance of basilisks
Biologists call 4 species basilisks large lizards, whose body length reaches 1.4-2 meters, but about 70% of the total length is a thin tail.
That is why, despite large sizes, these lizards are fragile and defenseless creatures.
Basilisks, like close relatives of iguanas, have a crest on their backs, but these lizards were nicknamed basilisks due to the leathery decoration on their heads that looks like a cockscomb.
Basilisks have long fingers on their hind legs; it even seems that they complicate the process of movement, but in reality it turns out to be the opposite.
Distribution and habitats of basilisks
All 4 species live in Central America, in South America and in Mexico. Recently, basilisks were brought to Florida, where they have adapted to more low temperatures, hiding in the forest floor.
Basilisks live exclusively in wet forests, settling in thickets along the banks of reservoirs. Most often they sit on the roots of bushes protruding from the water or on the lower branches of trees.
The Incredible Abilities of Basilisks
If the lizard is in danger, it instantly runs away. Basilisks have 2 escape strategies.
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If the water is far away, the lizard immediately buries itself in the forest floor or sand, while the nostrils are closed with special valves so that sand does not get into the nose. Buried in a shelter, the basilisk for a long time does not move. If there is a body of water nearby, the lizard rushes headlong into the water, while it runs along the surface of the water. The ability of basilisks to move through water without drowning seems incredible, but all individuals without exception can run this way.
What is noteworthy is that the basilisk runs through the water only on its hind legs, which is also not typical for reptiles. A basilisk can walk on water as easily as on the surface of soil. For this ability, basilisks were also nicknamed “Jesus lizards,” since it was he who was capable of such a miracle. But if faith in God helped Christ, then how does the basilisk cope?
In fact, the secret to the ability to run on a rein is quite simple. The long toes of the hind legs distribute the weight of the entire body. In addition, the basilisk protrudes scales on its fingers, which makes movement even easier. In addition, these lizards move their paws so quickly that they simply do not have time to drown. The basilisk's running speed reaches 1.5 meters per second.
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But running like this takes lizards great amount energy, so the basilisk can run through the water no more than 3-4 meters, then it dives under the water and begins to swim calmly, as if nothing had happened. It is worth noting that they can submerge completely in water, like crocodiles, and spend about half an hour under water until the predator leaves.
Since young basilisks weigh less than adults, their distance increases to 10-20 meters. Thanks to its rapid throw, the lizard distances itself from the enemy as much as possible, thereby escaping. In rare cases, basilisks also move on land on their hind legs, but their speed is much slower.
Basilisk lifestyle
Basilisks feed on insects, small snakes, birds, rodents, eggs, fruits and flowers. These lizards exhibit pronounced sexual dimorphism.
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Only males have ridges on their heads; females do not. And this is no coincidence, since males need to defend their territory, and with the help of combs they warn neighbors about their location. Females gather in groups near males, and they do not show aggression towards each other. Females do not have combs, since it is important for them to remain invisible in order to preserve their offspring.
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