Hypothetical adhesive mechanisms for wall crawlers? [Credit: hospitalGaming]

[u/Puijilaa]

Pictured is the creature from the GMod mod "Evil crawling thing" by HospitalGaming, (human for scale). I was messing around with it and it can run quite fast across all surfaces, and as pictured, suspend itself from ceilings. This inspired me, and it made me wonder about larger creatures that are shown to crawl on ceilings and walls.

I figured it would be a fun thought experiment for this subreddit to ask what sort of mechanism would allow a creature such a this to not just stick to walls and ceilings, but also move rapidly across them, attaching and detaching their feet very quickly. To not limit discussion, let's say this is an alien entity with potential biological properties not seen on Earth, or at least not to this extent, barring anything too fantastical like gravity inversion. Obviously it has many individual points of contact, but each individual point is rather small. Would a biological glue that is able to turn "on and off" at a moment's notice be possible? Or maybe molecular bonding would be more likely? Or any better ideas you can come up with? Rather than stooping to asking any LLM, I figured this might make an interesting discussion.

[u/Arnoor27]

I'd go with the gecko method.

Anatomy of a Gecko Foot

• Lamellae: Ridges or folds located on the bottom of a gecko's toes. • Setae: Millions of microscopic, hair-like bristles made of beta-keratin that cover the lamellae (each is about one-tenth the width of a human hair). • Spatulae: Tiny, split-end tips branching off from each seta, creating billions of individual contact points on a single foot. • Lipid Coating: An ultra-thin layer of hydrophobic (water-repelling) lipids coats the setae, helping repel water and maintain grip on wet surfaces.

How the Adhesion Works

• Van der Waals Forces: The spatulae get close enough to the molecules of a surface that the electrons synchronize, creating weak electrical-like attractions called Van der Waals forces. While a single spatula force is weak, billions working together can easily support the gecko's entire weight. • Peeling to Release: Geckos do not get permanently stuck because they peel their toes upward at a specific angle when taking a step. This action changes the angle of the setae and breaks the molecular contact effortlessly.