THE EXPLORATION of FUNCTIONAL NATURAL STRUCTURES Lukáš VOLESKÝ, Zuzana ANDRŠOVÁ, Lukáš STANISLAV, Pavel KEJZLAR, Dora
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23. - 25. 10. 2012, Brno, Czech Republic, EU THE EXPLORATION OF FUNCTIONAL NATURAL STRUCTURES Lukáš VOLESKÝ, Zuzana ANDRŠOVÁ, Lukáš STANISLAV, Pavel KEJZLAR, Dora KROISOVÁ Technical university of Liberec, Faculty of Mechanical Engineering, Department of material science; [email protected] Abstract Natural materials on Earth have been evolving for more than billion years. The nature has reached perfect solutions. In the nature has every solution some very specific meaning. Animals and plants, thanks to such developments, have been perfectly adapted to inhospitable conditions which are prevailing in different places on Earth. Structures, developed like this, have very specific properties, such as self-cleaning and super- hydrophobicity on lotus leaves or as water condensation on the elytra of fog basking beetle (onymacris unguicularis). This paper deals with the structural adaptation of limbs of housefly (musca domestica), spitting spider (scytodes thoracica), silverfish (lepisma saccharina) and seven-spot ladybird (coccinella septempunctata). Keywords: Silverfish, Seven-spot ladybird, Spitting spider, Housefly 1. INTRODUCTION The Bionics is relatively new scientific discipline, founded at the turn of 50 and 60 years of the 20th century. This discipline breaks down the boundaries between biology and technology. That´s why it is called Bionics. In the next few chapters there´s look into the fascinating world of diverse structures. This is allowed by use of modern imaging techniques, in this case the scanning electron microscope Zeiss Ultra Plus. We´ll look at the various adaptation of limbs of creatures which we call „primitive“, such as silverfish (lepisma saccharina), housefly (musca domestica), seven-spot ladybird (coccinella septempunctata) and the spitting spider (scytodes thoracica). 2. THE SILVERFISH The silverfish, also called as fismoth (lepisma saccharina) is a small, wingless insect. It belongs to the order of Thysanura. Its common name derives from the animal's silvery light grey and blue colour, combined with the fish-like appearance of its movements. Its food is based on primary organic substance originating from plants and contains carbohydrates and proteins. In household consumes the newspapers, books, glue, wallpapers, photographs, clothes and wool. What is so intereisting for us? It´s its ability to overcome vertical walls. 23. - 25. 10. 2012, Brno, Czech Republic, EU Fig.1: The Silverfish [1] Fish moth foot are ended by a small hook. These hooks are able to catch even small roughness and prevent slipping. This simple principle enables the silverfish to playfully move on vertical walls. Fig. 2: A small hook on the foot of silverfish. 3. THE HOUSEFLY The housefly (Musca domestica) is a small and very intrusive insect (Fig. 3), living in the vicinity of humans. The housefly belongs to the order of Diptera. Fig. 3.: The housefly. [2] 23. - 25. 10. 2012, Brno, Czech Republic, EU Fig. 4.: Small hooks on housefly feet. Fig. 5.: Miniature hair on housefly feet. The object of our interest are the feet again. As with the silverfish, are the feet of housefly ended by small hooks which enable to the housefly overcome a vertical wall (Fig.4). In the detail view we can observe a miniature fine hair (Fig. 5). These fine hair are broadened at the end. The housefly excretes a viscous liquid, which adheres to the pad and also to the fine hair. This enables the house fly to stay and move on the smooth vertical glass wall. 4. THE SEVEN-SPOT LADYBIRD The seven-spot ladybird (also called ladybug, coccinella septempunctata) is the most common ladybird in Europe. Its elytra are of a red colour, but punctuated with three black spots each, with one further spot being spread over the junction of the two, making a total of seven spots. Seven-spot ladybird belongs to the family of Coccinellidae. This family is spreaded worldwide. There are many species of ladybirds, different in color from yellow to red or brown. Coccinellidae are considered to be very beneficial insects because they feed on aphids and other insects which are prejudicial to fields, gardens and similar places. What could be inspiring on this beetle? Perhaps its adaptive feet. Fig. 6.: The seven-spot ladybird [3] Ladybird crawls on vertical surfaces such as walls. For this type of movement has a specially adapting legs (Fig. 7). If we´re looking on the feet of ladybird, we can observe the ending with tiny hooks, which can catch 23. - 25. 10. 2012, Brno, Czech Republic, EU a minimal inequality of the surface. These hooks are sufficient to the maintain on the walls, but not sufficient for climbing on smooth surfaces such as glass. Fig. 7.: The ending of ladybird´s foot. The style of ladybird´s walking is called tripedal. This movement allows fast transfer while maintaining maximum stability. During this movement legs alternately form triangles. During the first step the front and back legs on the right side and the middle leg on the left side are on the ground, while the other legs move forward. The second step is exactly the opposite, on the ground are middle right leg and left front and left back leg. However, ladybird doesn't keep this type of gait all the time. It´s able to adapt to circumstances (for example when it´s turning or avoiding an obstacle, four or more legs can touch the ground). Even more, the ladybird is able to adapt the style of walking in case of lost of limbs. 5. THE SPITTING SPIDER The spitting spider (scytodes thoracica) has its name because it spits a poisonous sticky silken substance over its prey. In our region we can meet the spitting spider rarely and only in heated buildings such as greenhouses, bakeries, warehouses or older homes. The spitting spider is common in the Mediterranean, it can be founded especially in the wild nature, eg. the steppe localities, under stones. [4] Fig. 8.: The spitting spider. [5] 23. - 25. 10. 2012, Brno, Czech Republic, EU Feet of the spitting spider are adapted for overcoming of smooth vertical surfaces. At the end of the foot, between claws (Fig. 9) is the scupula (Fig. 10), which is the densely hairy pad, terminating the leg. Fig. 9.: The ending of the leg of spitting spider. Fig. 10.: A hair growing from the last part of the leg. Individual hairs of scupula further branch into thousands of tiny hairs. These hairs have the dimension (transverse) about 220 nm (Fig. 11). Hairs are interacting with the surface by Van der Waals (electrostatic) forces. This enable the spider to maintain on smooth glass surfaces. Fig. 11: Detailed hair on spider´s leg 6. CONCLUSION The Homo Sapiens has been evolving for about 2,5 mil. years. In comparison with the nature, which had for the development and improvement of structures and materials about 7000 times longer period, it´s insignificant. So why should we laboriously invent new solutions when the solution of all possible situations 23. - 25. 10. 2012, Brno, Czech Republic, EU lies in front of us incorporated in natural materials and structures. As shown in this article, we only have to do very little - observe the structures and materials occurring in the nature, to understand their importance and especially their function. Nature has these structures and materials tested and tuned to perfection and more importantly, are consistent with the protection of the environment, so why not take advantage in our favor and overcome so for us right now unsolvable technical problems and shortcomings. By the way, nature has no patants on its solutions, so we don´t need to deal with copyright… ACKNOWLEDGEMENT This work was supported by the project SGS "Innovation in Material Engineering" LITERATURE [1] PROPHER. Propher [online] [cit. 2012-08-21]. Available from: http://www.propher.cz/4-produkty/8-rybenky.html [2] ARTHUR’S: FLY CLIP ART HOME. ARTHUR’S [online]. [cit. 2012-08-21]. Available from: http://www.arthursclipart.org/insects/flies/page_02.htm [3] Wildscreen [online]. [cit. 2012-09-15]. Available from: http://www.arkive.org/seven-spot-ladybird/coccinella- septempunctata/image-A6812.html [4] Natura Bohemica [online]. [cit. 2012-09-15]. Available from: http://www.naturabohemica.cz/scytodes-thoracica/ [5] BioLib [online]. [cit. 2012-09-15]. Available from: http://www.biolib.cz/cz/taxonimage/id80323/?taxonid=441 .