Your teeth tell a lot about you
Your teeth tell a lot about you
Dispersing seeds is a challenge when you’re stuck in one spot, but plants have evolved all sorts of mechanisms for it. Some rely on animals to carry their offspring away, others create their own vortex rings. The hairyflower wild petunia turns its fruit into a catapult. As the fruit dries out, layers inside it shrink, building up strain that bends the fruit outward. Once a raindrop strikes it, the pod bursts open, flinging out around twenty tiny, spinning, disk-shaped seeds. That spin is important for flight. The best-launched seeds may spin as quickly as 1600 times in a second, which helps stabilize them in a vertical orientation that minimizes their frontal area and reduces their drag. Researchers found that these vertically spinning seeds have almost half the drag force of a spherical seed of equal volume and density. That means the hairyflower wild petunia is able to spread its seeds much further without a larger investment in seed growth. (Image and research credit: E. Cooper et al., source; via NYTimes; submitted by Kam-Yung Soh)
Nectar-drinking bats, honey possums, and honeybees all use hair-like protrusions on their tongues to help them drink. In bats, these papillae have blood vessels that swell when drinking, stiffening the hairs. To investigate this drinking mechanism, researchers built their own version of a bat tongue by fabricating hairy surfaces and testing how well they trapped viscous oil when dipped and withdrawn. Through a combination of experiment and mathematical modeling, the researchers found that the optimal fluid uptake depended on the density of hairs, fluid viscosity, and the withdrawal speed. When they compared their results to actual bats, honey possums, and honeybees, they found that those animals’ tongues have hair densities very close to the predicted optimal value, suggesting that their model is capturing the important physical mechanisms that have driven evolutionary advantages for these species. (Image and research credit: A. Nasto et al.; submitted by Kam-Yung Soh)
the importance of bees in our ecosystem
Computational fluid dynamics (CFD) has been a valuable tool in engineering for decades, but its use is spreading to other fields as well. The image to the left shows a reconstruction of Parvancorina, a shield-shaped marine creature that lived some 550 million years ago. Fossil evidence alone cannot tell paleontologists whether this extinct creature could move through the water, and there are no living relatives that resemble the creature that scientists could study as an analogue. Instead, researchers turned to CFD to simulate flow over and around Parvancorina. They found that Parvancorina’s shape caused fast flow over the outer portions of its body and the slowest flow near its mouth. The results suggest that, not only was the creature mobile in the water, but that it was able to adjust its orientation to drive flow to different areas of its body. Paleontologists have only been using CFD for a decade or so, but already it’s giving us valuable insight into the creatures that roamed our planet hundreds of millions of years ago. (Image credit: M. De Stefano/Muse, I. Rahman; via Physics Today)
A scientific Miracle !!
Gall midge larvae, despite their lack of legs, are prodigious jumpers. These worm-like creatures use hydrostatic pressure to jump more than 30 body lengths. To do so, the larva curls itself into a loop, latching its mouth to its tail. It then shifts the fluids inside its body, flattening itself as the pressure builds. When the larva releases its tail, it flies into the air at about 1 m/s. The human equivalent of a gall midge larva’s jump would be about 60 meters, far beyond the world record long jump of less than 9 meters (with a running start). The larva’s technique is a relatively simple but highly effective one that might be useful in applications like soft robotics. (Video credit: Science; research credit: G. Farley et al.)
Saguaro cacti can grow 15 meters tall, and despite their shallow root systems can withstand storm winds up to 38 meters per second without being blown over. Grooves in the cacti’s surface may contribute to its resilience, by adding structural support and/or through reducing aerodynamic loads. The latter theory mirrors the concept of dimples on a golf ball; namely, grooves create turbulence in the flow near the cactus, which allows air flow to track further around the cactus before separating. The result is less drag for a given wind speed than a smooth cactus would experience.
Indeed, recent experiments on a grooved cylinder with a pneumatically-controlled shape showed exactly that; the morphable cylinder’s drag was consistently significantly lower than fixed samples. Cacti do change their shapes somewhat as their water content changes, but they don’t have the ability for up-to-the-minute alterations. Nevertheless, their adaptations can inspire engineered creations that morph to reduce wind impact. (Image credit: A. Levine; research credit: M. Guttag and P. Reis)