The male desert sand grouse may be less conspicuous, but his belly feathers give him the unique ability to absorb and carry water. For the first time, researchers have closely examined the structure of feathers to see how they absorb water and whether the process is suitable for human use.
When you think of feathers, you probably think of their ability to repel water. The male southern sun grouse’s ventral feathers are not. He visits drinking holes and absorbs water into his feathers, and across the desert he flies over 12 miles (20 km), leaving enough water to satisfy a nest full of crowing chicks. Considering you can keep about 15% of your body weight in the water while flying at speeds of about 40 mph (64 kph), this is an amazing feat.
The sand grouse’s ability to carry water was first noted in 1896 by ornithologist and conservationist Edmund Meade-Waldo when they were kept in captivity. Sadly, no one believed him when he reported his findings to others. It was in 1967 that Tom Cade and Gordon McLean reported their observations of sand grouse at watering holes in the Journal. Condorwhich the scientific community has noticed.
Now, researchers at Johns Hopkins University and MIT have used the latest high-resolution microscopy and 3D techniques to take an unprecedented look at what gives these feathers their water-holding capacity. They used adult ventral feathers of the Namaquasand grouse common in Namibia, Botswana and South Africa.
Using scanning electron microscopy, micro-computed tomography, light microscopy, and 3D videography, the researchers were able to determine the size of the feather shaft in the abdomen, which is a fraction of the width of a human hair, and even smaller hairs. I could see feathers. These tiny hooks provide mechanical structure and aerodynamic integrity.
Scanning electron micrograph of the medial zone of a dried Namaxa sand grouse ventral feather showing the barb shaft, the spiral coil of twigs adjacent to the barb shaft, and the straight fibrous extension of the twig beyond the spiral coil.
Johns Hopkins University
They then performed the delicate process of immersing the dried feathers in and out of water, observing at high magnification the structure of the feathers absorbed the liquid.
“When you do this kind of work, you can’t even breathe, or you’ll blow it off,” said Jochen Mueller, a co-author of the study.
In general, bird wings have a central axis from which small barbs emanate, and smaller barbs emanate from them. However, in the dry sun grouse plumage, there are twigs inside the plumage that spiral and straighten at the base. In the outer zone, the twigs are straight and much longer, arranged in a fringe.
The researchers found that in wet feathers, the inner zone barbs are small and flexible, so surface tension is sufficient to bend the straight sections into water-retaining teardrop-shaped structures. . The thorns and twigs in the outer zone curled around the structure in the inner zone, helping to keep the water in place.
“It’s fascinating to see how nature has created structures that are so efficient at taking in and retaining water,” Mueller said. We think it could lead to new bio-inspired creations.”
It was previously thought that surface tension allowed feathers to retain water, but this study shows that the flexibility of different parts of feathers is important.
The findings could lead to useful human applications, the researchers say. For example, in desert areas where water is scarce but fog and dew occur regularly, such as the Atacama Desert in Chile, adaptations of feather structures can be incorporated into water catchment networks.
“You can imagine this is a way to improve these systems,” said study co-author Lorna Gibson. It can be effective.”
Another potential use is the design of water bottles that hold large amounts of liquid, but rely on the structure of the feathers to keep the water from moving around when someone is jogging.
“We were thrilled to see that level of detail,” Muller said. “This is what we need to understand to create new materials using these principles.”
The researchers intend to 3D print similar structures to pursue commercial applications of their findings.
This research Royal Society journal interfaceand the video below, produced by Johns Hopkins University, shows how the scientists conducted their research and includes some of the images they collected.
How African Birds Inspire Better Water Bottles
Source: Johns Hopkins University, MIT
