The Toes of the Tokay

A team of scientists has recently uncovered new evidence of how geckos can deftly scuttle around vertical surfaces without falling off.¹ The animals studied to reveal this ‘new trick to their stick’ were tokay geckos (Gekko gecko). These are the largest known species of gecko, so make excellent test subjects.

Tokays are called this because their loud, unusual call sounds like “tokayyyy!”² They are attractively coloured, having blueish skin with orange patches (fig. 1). 

I first came across tokay geckos while visiting Coron, an island of my wife’s native country, the Philippines. She and I encountered one in our hotel room, an uninvited, noisy guest some 30 cm (12 in) in length. I gently persuaded our reptilian roommate, lurking behind a wall-mounted TV, to vacate. We were both stunned to see it scurry up the walls and across window glass, despite its size.

Tokays are known for their powerful bite, so with towel in hand, I was relieved to be able to capture it safely and pop it outside unharmed. After such an ‘up-close-and-personal’ with this lively leaping lizard, I was intrigued to read of the latest scientific discoveries.

The research article states that gecko feet, “possess the most hierarchically integrated natural structures that span seven orders of magnitude in size…”1 The images opposite demonstrate what that means. The ‘hierarchical’ structure of a gecko’s foot (fig. 2) is shown photographed by an electron microscope (fig. 3). Many rows of extremely fine hairs (setae) can be seen, about 1/10 of a millimetre long and densely packed, with 5,000 per square mm (three million per square inch). The end of each seta has up to 1,000 branches, ending in spoon-like structures (spatulae), approximately 0.2–0.5 µm (micrometres—less than 1/50,000 inch) long.⁴ All of this is constructed at the molecular level from proteins by molecular machinery, encoded on the DNA—an astounding biological fact!

When these microscopic structures come into contact with a surface, van der Waals (vdW) forces come into play. These are weak electrostatic forces that operate at very small distances—see ‘What are van der Waals forces?’ below.

The fact that geckos’ spatulae are so numerous means that a huge surface area is available, producing an overall large attracting force.⁵ Tokays demonstrate this in that their entire weight can be suspended from a single, upwardly pointing toe, in contact with a smooth, vertical surface.1

Previously, it was discovered that tokay feet and skin have superhero-like abilities to repel liquids, leading to new gecko-inspired materials.5 Gecko toe structures have inspired new materials (‘nano-tape’) that take advantage of vdW forces.⁶Under normal conditions, the tape is completely non-sticky, but under shear force, the material’s engineered coating induces vdW forces, enabling the tape to stick strongly to any surface. This allows objects to be lifted or pulled, or surfaces to be climbed by robots (or people) using the tape. As soon as the shear force is reduced, the tape simply falls away from the surface⁷ in similar fashion to how geckos ‘unstick’ their feet.3 The new data discussed in this article will enable robots to better climb vertical, variable textured surfaces.

The implications of all this are obvious; clever robotics and materials cannot arise by chance, but require intelligent creator(s). How much more the geckos’ biological design, which is incomparably superior to human-made objects. Nonetheless, the scientists’ paper offers a platitude to evolution for gecko toe design, saying it supposedly demonstrates “… a creative evolutionary solution to a functional problem.”¹ If the word “evolutionary” were redacted, this statement would be entirely correct—the most creative solutions came from the Creator! The scientists’ clever research points to divine design, which should lead us to praise the Designer.

[TBC: For full article and footnotes:]

https://creation.com/toes-of-the-tokay