[SciShow Intro plays] Hank: Long before there were skyscrapers and strip malls and combination Pizza Hut/Taco Bells, nature had its own architects, all kinds of creatures create all kinds of different structures for a living, raising kids, or maybe just the occasional hookup. But centimeter for centimeter, some of the mightiest and most delightfully complex structures ever built have been erected by insects. For example, let us consider the geometry of bees. So you have seen the wondrous creation that is the honey comb, where bees store their honey, and you've probably noticed its perfect symmetry, each cell having six edges, all less than .1mm thick, meeting at exactly an angle of 120 degrees, but do you know why they chose the hexagon for this structure? Your math teacher does. It's all about maximizing efficiency. For each gram of wax that a bee produces to build a honey comb, it needs to consume at least 6 grams of honey. So bees need the perfect shape that can be repeated endlessly over a flat area, and there are only three shapes that can fit together without leaving gaps: squares, equilateral triangles, and hexagons. And it turns out, hexagons have a smaller total perimeter than either triangles or squares, which means that you can fit a lot more of them in a given area. Ancient Greek scientists predicted this more than 2000 years ago, but it wasn't until 1999, when University of Michigan mathematician Thomas Hales wrote a 19 page proof that the hexagon is more compact that we know for sure. You may also be familiar with termites. Probably in a negative connotation, but it's hard not to respect these insects for the mounds that they sometimes build. There are more than a thousand species of termites, and several species in Africa and Australia have constructed mounds that surpass 9 meters in height. If humans were to build a skyscraper on that scale, it would be more than 1.5 kilometers high. But as impressive as this is, the real genius of termite architecture is that the mounds feature a ventilation system so efficient that humans are actually copying it. Termites require the inside of their homes to maintain a constant temperature of 30.5 degrees Celsius. Why? Because termites are also fungus farmers, they grow it as one of their major food sources. Because outside temperatures in both Africa and Australia can vary between 2 and 40 degrees Celsius, the termites construct a system in and around the mound so that the internal temperature always stays the same. Using vents and channels that can regulated throughout the day, air comes in at the base of the structure, and is sucked down into tunnels with muddy walls. As the air moves through the tunnels of wet mud, the air temperature is lowered through evaporative cooling. Meanwhile, warmer air inside the mound is drawn up by convection currents and escapes through the opening, or flue, at the very top. If the temperature gets too hot or cold, the termites can easily dig new vents or plug up old ones in order to regulate their climate. In Zimbabwe, the country's largest shopping and office complex is modeled on this design, with no conventional air conditioning or heating system, the Eastgate center was built with thick concrete walls that have high heat capacity, the building draws in outside air through fans on the first floor and is warmed or cooled, depending on which is hotter, the concrete or the air. At night, the warm air is vented out through chimneys, just like in the termite mound. Finally, we could spend an entire episode talking about spider structures and the science of silk, but I have to tell you how in 2007, a 180 meter long spider web came to be in Lake Tawakoni State Park in East Texas. Spiders tend to be pretty territorial, sometimes even cannibalistically territorial, when it comes to building webs for catching food. But something interesting happened in 2007, a particularly wet summer that resulted in a major surplus of mosquitoes, crickets, and caterpillar larvae. Instead of fighting over the abundance of food, millions of spiders from at least a dozen species cooperated by creating a sheet web to catch food collectively. While not unprecedented, this cooperative web building is extremely rare and also, as you can see, really creepy. That web, in some places, was thick enough to block out the sun. Hopefully, that's not too creepy, and thank you for watching this episode of SciShow. If you have any questions or comments for us, you can find us on Facebook and Twitter, and of course, down in the comments below, and if you wanted to continue getting smarter with us, you can go to YouTube.com/SciShow and subscribe. [SciShow Endscreen]