About This Collection
How can we gain ideas from nature for retrofitting our homes, buildings, and communities with new technology that lightens our environmental footprint? For example, how does nature use insulation to reduce energy use? How does it reduce water usage? How does it manage resources in a closed-loop system, leaving nothing to waste? Explore this collection to learn how nature does these things and more. Consider how emulating these strategies in human designs could make our existing buildings and communities more life-friendly.
This collection has 19 strategies
The bracts of Lobelia telekii protect its flowers from wind and cold via long, hair-like shape.
The down feathers of eider ducks provide insulation due to lack of barbules and ability to fluff.
"One of the warmest nests in the world, the eider duck's nest is lined with soft down from the female eider duck's breast. Eider ducks nest on tundra-covered islands in the arctic, so it is not surprising that they have developed the warmest known down. When they hatch, the chicks already have their own eiderdown coats." (Foy and Oxford Scientific Films 1982:111) Learn More
Flowers of snow lotus plants protect from the cold via thick, furry insulation.
Pigments in frog skin change color in response to hormones by moving melanin grains around cells.
Mounds of compass termites provide heating and cooling at appropriate times of day thanks to orientation with respect to the sun.
"The termites Amitermes meridionalis and A. laurensis construct remarkable meridional or 'magnetic' mounds in northern Australia. These mounds vary geographically in mean orientation in a manner that suggests such variation is an adaptive response to local environmental conditions. Theoretical modelling of solar irradiance and mound rotation experiments show that maintenance of an eastern face temperature plateau during the dry season is the most likely physical basis for the mound orientation response. Subsequent heat transfer analysis shows that habitat wind speed and shading conditions also affect face temperature gradients such as the rate of eastern face temperature change. It is then demonstrated that the geographic variation in mean mound orientation follows the geographic variation in long-term wind speed and shading conditions across northern Australia such that an eastern face temperature plateau is maintained in all locations." (Jacklyn 1992:385) Learn More
The scales of pine cones flex passively in response to changes in moisture levels via a two-layered structure.
"The mechanism of bending therefore seems to depend on the way that the orientation of cellulose microfibrils controls the hygroscopic expansion of the cells in the two layers. In sclerids, the microfibrils are wound around the cell (high winding angle) allowing it to elongate when damp. Fibres have the microfibrils orientated along the cell (low winding angle) which resists elongation. The ovuliferous scale therefore functions as a bilayer similar to a bimetallic strip, but responding to humidity instead of heat." (Dawson et al. 1997:668) Learn More
The body of bumblebees maintains a regular temperature via counter-current heat exchange and a heat-shunting mechanism.
"2. However, the counter-current heat exchanger can be physiologically circumvented. Exogenously heated bumblebees prevented overheating of the thorax by shunting heat into the abdomen. They also regurgitated fluid, which helped to reduce head temperature but had little effect on thoracic temperature.
"3. Temperature increases in the ventrum of the abdomen occurred in steps exactly coinciding with the beats of the ventral diaphragm, and with the abdominal 'ventilatory' pumping movements when these were present. The ability to prevent overheating of the thorax by transport of heat to the abdomen was abolished when the heart was made inoperative.
"4. At low thoracic temperatures the ventral diaphragm beat at a wide range of rates and with varying interbeat intervals, while the heart beat at a high frequency relative to the ventral diaphragm, but at a very low amplitude. However, when thoracic temperature exceeded 43 °C the amplitudes of both were high, and the interbeat intervals as well as the beating frequencies of the two pulsatile organs became identical in any one bee. Furthermore, heated bees engaged in vigorous abdominal pumping at the same frequency as that of their heart and ventral diaphragm pulsations.
"5. The results indicate that the anatomical counter-current heat exchanger is reduced or eliminated during heat stress by 'chopping' the blood flow into pulses, and the blood pulses are shunted through the petiole alternately by way of a switch mechanism." (Heinrich 1976:561) Learn More
The wing scales of a green birdwing butterfly help regulate body heat by using a honeycomb structure to enhance black pigments found in the wings.
"In our previous studies, we have already discovered that structurally assisted blackness is a common phenomenon in black butterfly wings and furthermore an ideal structure for improving the blackness. Compared with the porous structures in other species of butterflies, the structure in the cover scales of the black wings of butterfly Ornithoptera goliath is mainly comprised of adjacent inverse V-type ridges, which can effectively reduce reflection, while at the same time keep transmission at a relatively low level. However, limited by the optical properties of the natural chitin/melanin composite, the effect of the structure in producing black materials is far from fully exploited." (Zhao et al. 2010:877) Learn More
The nasal turbinates of the northern elephant seal reduce water loss via countercurrent heat exchange.
Respiration can be a significant cause of water loss. Species like the elephant seal, penguin, reindeer, camel, kangaroo rat have a particularly effective so-called temporal counter-current exchange mechanism in their nasal passages that minimizes the amount of water lost from the respiratory system. The nasal turbinates are important structural and functional components of this mechanism. This is a series of boney, shelf-like structures in the nasal passageway covered with a well-vascularized layer of moist tissue and mucus. Inhaled air passing over this surface is warmed and moistened, and the surfaces cool due to evaporation. When the animal exhales, warm, water-saturated air from the lungs passes across the cooled nasal turbinate surfaces and water condenses out of it, staying within the nasal passages rather than being lost to the outside air. Those species with the highest percentage respiratory water recovery (e.g., 92% in the elephant seal compared to 24% in the sheep), have the most complex nasal turbinate structure. The key features of the more elaborate nasal turbinates are their very large surface area and the short distance from that surface to the middle of the airstream.
Designs of nasal turbinates in marine mammals like the elephant seal may offer inspiration for the design of more effective human-constructed water and heat recapturing systems. Learn More
Down feathers of geese insulate through special architecture.
Comparison of keratin structure in down feathers and mammal hair. Artist: Emily Harrington. Copyright: All rights reserved. See gallery for details.
The eye of a lobster focuses reflected light onto the retina using a perfect geometric configuration of square tubes.
"These well-arranged squares are in fact the ends of tiny square tubes forming a structure resembling a honeycomb. At first glance, the honeycomb appears to be made up of hexagons, although these are actually the front faces of hexagonal prisms. In the lobster's eye, there are the squares in place of hexagons.
"Even more intriguing is that the sides of each one of these square tubes are like mirrors that reflect the incoming light. This reflected light is focused onto the retina flawlessly. The sides of the tubes inside the eye are lodged at such perfect angles that they all focus onto a single point.
"The extraordinary nature of the design of this system is quite indisputable. All of these perfect square tubes have a layer that works just like a mirror. Furthermore, each one of these cells is sited by means of precise geometrical alignments so that they all focus the light at a single point." (Yahya 2002:11)
Lobster eye illustration. Artist: Emily Harrington. Copyright: All rights reserved. See gallery for details.
Lingual retes of gray whales precool blood in the tongue to avoid heat loss via counter-current heat exchange.
The presence of very long, small diameter arterial and venous vessels in close proximity with low flow is key to the efficient recapture of heat and maintenance of a cool tongue surface. Learn More
The leaves of some bromeliads capture water and nutrients in a storage tank via hydrophobic leaf surfaces.
Species diversity in tropical rainforests maximizes limited resources by collecting nutrients and water immediately upon availability via superficial root systems
The soil ecosystem supports plant growth through interactions of millions of organisms that work together to break down chemicals and aerate the soil.
The pillar-like leaves of window plants enhance photosynthesis by filtering sunlight down a series of translucent crystals of oxalic acid.
Body of bull trout decreases energy required for swimming by using vortices in its liquid environment.
Check out these videos to see the trout's slalom movement in action.
This summary was contributed by Ashley Meyers.
Cacti stay cool by having ribs that provide shade and enhance heat radiation.
"Ribs and tubercles are another type of surface modification that can affect surface temperature. Based on previous data (Lewis and Nobel 1977), the convection coefficient for Ferocactus without spines is 2.8x higher than expected for a smooth cylinder of the same diameter under field conditions (Nobel 1974). For a spineless Mammillaria, the convection coefficient was ~2.6x higher than for a smooth cylinder. Thus, surface irregularities indeed favor convective heat loss and tend to minimize stem-to-air temperature differences, although the effect is lessened somewhat by the presence of spines (Hadley 1972). Ribs of Ferocactus wizlizenii and Carnegiea can be about 30% closer together on the southwest compared to the northeast side (Walter 1931); this could enhance the convective cooling at the region subjected to the highest stem surface temperatures by providing more area for heat exchange." (Nobel 1973:993)
Mechanism for cooling in torch cactus. Artist: Emily Harrington. Copyright: All rights reserved. See gallery for details.
"Presumably as a result of the turbulence and air flow patterns created by the ribbing, hc [the heat convection coeffcient], expressed on a unit surface area basis was 67% greater than for a smooth cylinder of the same outside diameter under the turbulence intensity appropriate to field conditions (12). Since the ribbed surface area for this barrel cactus was 54% greater than that of the circumscribing polygonal surface, the total convective loss per level would be just over 2.5-fold higher than for a smooth cylinder." (Lewis and Nobel 1997:615)
"The simulated rib elimination reduced both the convection and the latent heat terms [of an energy budget model] by reducing the actual plant surface area to that of the circumscribing polygonal surface. Most of the rather small increase in surface temperature at night in the absence of ribs...was due to the accompanying decrease in latent heat loss, while the 1 to 2 C rise during the day was due to the decrease in heat convection from the stem. The importance of ribbing for daytime convective cooling is also seen by comparing the spineless plants...where rib removal increased the average daily surface temperature by 0.8 C for the summer day." (Lewis and Nobel 1997:615) Learn More
The carotid rete of the Thomson's gazelle cools its brain via counter-current heat exchange.
The brain is a part of the body that is particularly sensitive to high temperature. Hence some ungulates, like the Thomson’s gazelle, use a counter-current heat exchanging structure known as the carotid rete to keep the brain cooler than the body. The rete is a configuration of arteries and veins in a sinus at the base of the brain. Warm blood flowing to the brain travels from the carotid artery into a network of small arteries within the sinus, where it transfers some of its heat to cooler venous blood flowing the opposite direction as it returns from the nasal passages. The cooled arterial blood then continues toward the brain.
In the running Thomson’s gazelle, body temperature rises more than brain temperature such that a difference between brain and body temperature has been measured at 2.7° C. A predator like the cheetah must stop running when its body and brain temperature reaches 40.5° C, but the gazelle can keep running as its body temperature rises above 43° without its brain temperature exceeding 40.5°. The ability to keep a cool head can thus give the gazelle a survival edge in these predatory pursuits as he can outlast the cheetah who cannot maintain a cooler brain.
Counter-current heat exchangers can be found in many organisms in many configurations. While such mechanisms are well known to engineers, a close look at the design of those used by nature may be useful in designing thermal control systems of human habitations. (Courtesy of The Biomimicry Institute) Learn More