How do spiders get up surfaces to make their webs? Many animals, including spiders, have adaptations that allow them to stick to and climb up surfaces. In some animals, liquid is released from the foot and creates a force holding them to the surface. However, spiders use “dry adhesion” and don’t produce such a liquid, so researchers from the University of Kiel in Germany wondered how they stayed up.
Using a scanning electron microscope, the researchers looked at the legs of a spider. They found that at the base of each leg there were many small fibers. Having more points of contact pushing against a surface improves adhesion, so spiders likely found it advantageous to have a lot of these fibers. Additionally, the fibers pointed in many different directions, which may allow the spiders to have good contact with a surface even if they change the direction of movement.
The researchers mimicked the structure of a spider leg by attaching fibers like those found in the microscopy images to a glove. When they tested the amount of weight the glove could support, they determined it could hold an object as heavy as an adult human. The authors note that similar fiber designs, like many designs nature has given animals to navigate their environments, could be used in human structures that need strong attachment to surfaces.
Managing Correspondent: Emily Kerr
Press Article: A spider’s feet hold a hairy, sticky secret
Scientific Article: Adhesion of Individual Attachment Setae of the Spider Cupiennius salei to Substrates With Different Roughness and Surface Energy
Image Credit: “Spider” by sez9 is licensed under CC BY-NC 2.0
While I think I understand how the hairs work against the surface tension of water to enable them to walk or run along the surface, I struggle to understand how they can in the blink of an eye dive under the surface to catch something several inches down. Do they lay the hairs back just eliminating a large surface area, or is there some electro chemical action that change the feet and legs from hydrophobic to hydrophylic? although Hydrophylic isn’t the right word, since they obviously don’t dissolve, but rather wet-out.
Then there is the issue of displacement. I would imagine spiders can contract the volume of their abdomens to decrease flotation, although their thorax is rigid or fixed.
if you can somehow mimic those fibers with a electric current so that you can make the action of flexing the hairs like a spider to chose when to stick and when not to
How do jumping spiders defy gravity when on a wall or ceiling?