Echinoderm lizard, endemic to Australia, has sandy skin covered with triangular spikes. In the desert, like a bundle of walking thorns.
In 1840, when the Echinosper Lizard was exhibited for the first time in London, the audience was startled by its appearance and thought that this lizard, which had never been seen before, looked as terrible as a devil, so they gave it a name called "moloch horridus". "moloch" is the name of the evil Vulcan in Paradise Lost, and since then, the scientific name of the spiny lizard has been called the Australian thorn devil lizard.
The truth is that, apart from its prickly skin, the devil lizard doesn't look like a devil at all. White and white with spikes, the result is still unable to escape the fate of being eaten by large lizards and poisonous snakes.
The Australian devil lizard lives in the desert of Western Australia, with its tail attached, only 20 cm long and weighing 70 grams, just right to fit in the palm of your hand. The small and light body of the demon lizard has very little strength, and its courage is smaller than its strength. Every day, hiding under the sand or in the bushes, I only dare to catch a little ant to eat.
A harmless demon lizard with scary gear all designed to defend against enemies, including skin color, spiny spines, and a fake head.
Like other lizards, the demon lizard changes color. It has two colors, bright yellow-red when the weather is warm, and dark greenish brown when the weather is cold, which is consistent with the color of the surrounding environment. If you don't pay attention, it will be difficult to spot the demon lizard among the dead branches of the fallen leaves.
Wearing a barbed camouflage costume disguised as a background wasn't safe enough, and the devil lizard added a new trick to itself: grow a fake head behind its neck. The sarcoma, which is not much smaller than the real head, is its false head, and when danger comes, the devil lizard lowers its head, hides it between its front legs, and uses the false head to confuse the enemy. The enemy bites the prosthesis, and it can take the opportunity to discard the prosthesis and escape.
In addition to its disguised appearance, the devil lizard also has to confuse its enemies when walking, and it invents a kind of devil's step: swinging back and forth, one step and three stops. The tail cocked up, slowly and hesitantly stepped on all fours, and stopped in the air between hands and feet. After one pause, the body moves back and forth twice, and then continues to move forward. The devil lizard walks on the red desert of Australia with its characteristic footsteps.
The lizard is a warming animal, and weather is the main factor affecting its activity. Dependent on the warming of the environment, the magic lizard is afraid of both cold and heat, and in the coldest winters in Western Australia (June and July in the southern hemisphere) and the hottest summers (January and February), it will retreat to the underground caves it has dug, rarely going out, and only going out in the spring and autumn to find a companion.
The magic lizard, which does not like sports, has a daily life area of no more than 10 meters. In the living area, only three places are needed: home, restaurant, and bathroom. The bush is its home, surrounded by several ant pathways, which is its restaurant, and there is a fixed bathroom in the corner of the community. When the sun first rises, the devil lizard comes out of the bushes, first lying on his stomach to bask in the sun, charging and heating up, waiting for the cold body to wake up and warm up. When the body temperature rises to 33 degrees, the magic lizard heads forward to the fixed bathroom 10 meters from home. After cleaning up the personal hygiene, the same way back to the bushes, and then did not hurry to the ant passage to find the ants to eat.
The devil lizard is very picky and eats nothing but ants. Among the many varieties of ants, it loves the small yellow rainbow stink ants (iridomyrmex flavipes), which can eat 24 to 45 per minute and 1,000 to 2,500 ants for a meal. The devil lizard has a short, sticky tongue that is used to stick ants. The tongues of other lizards can be boiled with water to drink, while the tongue of the devil lizard, except for sticky ants, cannot even drink water.
The magic lizard, which does not use its tongue to roll water, invented a unique way to drink water: absorb water with its feet, reverse the water from the skin to the mouth, and swallow the water normally. In the GIF you can see the magic lizard standing in muddy water, moving up and down the mouth of its throat, which is exactly the water it is swallowing from the skin. The devil lizard standing in the water is like a plant rooted in the soil, absorbing water from the roots and transporting it to the leaves through capillary action. [Headlines - France is Bacon - Please do not reprint other platforms without authorization]
Dew condenses on the leaves of flowers and trees, moisture condenses on the surface of glass metal, and the skin of beetles and lizards, like leaves and glass, condenses moisture from the air and condenses into droplets. The temperature difference between day and night in the desert is very large, and the warming magic lizard has a body temperature drops at night, and its skin is as cold as at night. When the sun rises during the day, temperatures rise faster than body temperature, and moisture in the warm air condenses on the cold skin. However, the devil's tongue cannot lick the dew on the skin, and can only rely on the skin to automatically deliver water to the mouth. The scales on its body have small grooves between folds, and the fold grooves are connected into a capillary-like network, and the water is transported in reverse through capillary action.
The capillary phenomenon of transporting water is caused by the different forces of water molecules on the skin layer than the water molecules inside the liquid. Simply put, the gravitational pull of solid skin on water molecules is greater than the gravitational force of water molecules inside liquids, and water can gradually climb up along the capillary network.
The scale skin of the devil lizard is divided into 3 layers, the outer layer is β keratin, the inner layer is α keratin, and the middle layer is spacer layer. Coarse, thick keratin scales lock in moisture in the lizard's body, minimizing water loss. Interestingly, it is this skin made up of waterproof scales that absorbs water like a sponge. The skin of the devil lizard, the scales themselves do not absorb water, but the scales will grow honeycomb-like miniature structures, and the honeycomb-like grooves can hold a lot of water.
Above is a microscopic photo of the skin of the devil lizard taken by the team at RWTH Aachen University in Germany, where dense honeycomb structures can be seen. When water droplets come into contact with the skin, they are quickly absorbed by the skin and remain in the honeycomb voids.
The team dropped a drop of water (5 μl) on the skin of the magic lizard, and the gif can clearly see that the water droplets were immediately absorbed. Compared to scales without a honeycomb structure, the ability of the devil's skin to condense moisture is increased by 100%. The honeycomb structure can maintain the physical stability of the water film, so that the water stays on the surface of the body without volatilization.
The skin details are shown in the figure above, and Figure d is the width of the capillary, ranging from 26.3 μm to 327.8 μm.
The picture above is a schematic diagram of capillary water transport, water spreads along the capillaries in both horizontal and vertical directions, the width of the capillaries in the two directions is not the same, the horizontal direction is narrower, and the thinner the capillary is transported faster.
How fast is a capillary measuring in microns in width? The team used microscopic cameras to record the diffusion rate of the water droplets on the surface of the skin. The speed of water diffusion is different in different parts of the body of the devil lizard, the fastest transmission site is in the mouth: 2.18mm/s, the slowest water transmission speed in the tail: 1.80mm/s, and the body side speed is: 2.15mm/s. That is: when moisture is close to the mouth, it speeds up the flow rate.
The magic lizard not only absorbs moisture from the air, but also from damp sand. It sometimes cuts a pit in the sand, digs out the wet sand in the ground, and shovels the wet sand onto the back, and the scales on the backrest absorb the moisture in the sand. The team measured the lizard's water absorption rate in the lab and equipped it with the wettest sand. Standing on four feet in sand with a moisture content of 22%, the magic lizard can collect up to 1.84% of its body weight. There is very little moisture, not even enough wetness, and only 59% of the capillary on the surface of the skin can be filled. It's different if you shovel wet sand onto your back, and with the help of gravity, the moisture in the wet sand can fill the capillary network on your skin and then deliver the water to the mouth of the devil lizard.
If you can't find wet sand, just rely on the moisture in the air, plus the moisture of food ants, not enough to replenish the amount of water that the devil lizard's body needs. When there is a shortage of water, the devil lizard will go to find a puddle of water, and as long as it can wet its feet, it can drink nectar.
The team placed 12 magic lizards in a quagmire 3 mm deep and weighed them 1 hour later. Some of the 12 demon lizards were thirsty, and some were not. Although water is absorbed through the feet and transported to the mouth, the devil lizards that are not thirsty are fed water and do not drink. Of the 12 magic lizards, 5 had their throats moving and swallowing water, while the remaining 7 did not swallow and drink water.
Weighed 1 hour after being put into the mire, the devil lizards that did not drink water only absorbed and stored water on their skin, gained 3.66% weight, and after blowing their skin dry, the weight remained basically unchanged. The devil lizard that drank water gained 6.84% weight, and after blowing the skin dry, it gained 3.79%. That is to say, the thirsty devil lizard can drink 3.79% of the weight of water at a time.
Whether you are thirsty or not, puddles of water accumulate on the sand after the rain, which is a pleasant thing for the devil lizard. Step in the mud, absorb the water into the skin when you are not thirsty, and drink it directly when you are thirsty. A barbed discolored scale, not only the camouflage costume of the devil lizard, but also its large kettle.
For organisms living in arid areas, drinking water is the number one problem. The small devil lizard weighing only 3 pairs simply folds the scales and changes the epidermal structure of the scales, turning the skin into a water absorption network, solving the problem of drinking water.
Nature has always been ahead of us, and even a skin fold is exquisitely done.
#Science interesting # #头条辟谣 #
Resources:
1：“moisture harvesting and water transport through specialized micro-structures on the integument of lizards”，philipp comanns，et al., beilstein j nanotechnol, 2011
2：“cutaneous water collection by a moisture-harvesting lizard, the thorny devil (moloch horridus)”，philipp comanns, philip c. withers, falk j. esser, werner baumgartner， journal of experimental biology，2016
3：“directional, passive liquid transport: the texas horned lizard as a model for a biomimetic ‘liquid diode’”，philipp comanns，et al., journal of the royal society interface，2015
4：“adsorption and movement of water by skin of the australian thorny devil (agamidae: moloch horridus)”philipp comanns，et al., royal society open science，2017
P.S. Today we update the secret series of articles in nature, which is the 27th: Lizards drinking water with their feet. In the BBC documentary "7 Worlds, 1 Planet", Episode 4 Oceania, the figure of the Australian magic lizard appeared.