Crawling insects (let's call them 2D navigation specialists) on land are prey to flying insects (3D navigation specialists). But these 3D specialist predators require more energy to navigate and maintain flying ability.
Spiders invert this relationship -- they are 2D specialists that slice a 3D space with a trap, capturing 3D specialists without expending energy to navigate their prey's space.
Not quite a free lunch -- it takes some prep work in the lifetime of a spider to survive. Losing your web makes you suspect to getting wrecked by robber flies until you build a new one.
On a more science fiction note, I've wondered about generalizing this 2D/3D existence relationship into humans interacting with a hyper-dimensional entity. Will we also have to evolve to build traps against the perception weaknesses of our 4-dimensional invaders?
Anyway, I've thought about the level of fidelity of information a spider could get from vibrations on a web. It's probably a function of nervous system ability and sensitivity for the spider to discern frequencies of forces impacted unto it by the web, as well as the frequencies filtered by the web itself. Looking forward to reading the paper.
Not all spiders are 2d specialists who hunt with webs. Jumping spiders display extraordinary spatial reasoning in conjunction with excellent vision, which they use to stalk prey. Jumping spiders have been known to sit motionless for up to half an hour, scanning the landscape to plan the best route to something they can see (the FOV of their hi-res front-facing eyes is quite narrow, so this scanning is necessary to gather the required information).
"Spiders invert this relationship -- they are 2D specialists that slice a 3D space with a trap, capturing 3D specialists without expending energy to navigate their prey's space."
I think that's a great way to put it, although "spiders" really should say "orb weaving spiders".
Jumping spiders don't build a web, they are active hunters in the 3D space with the ability to plan several steps ahead. Although they can't fly, they definitely hunt in 3D and don't really conserve energy.
Huntsman spiders are also active hunters, but mostly in 2D and waiting from an ambush position. They don't build a web. Neither do crab spiders, but I'd agree that these two families of spiders are trap-based and largely passive, even if the trap is not a web.
Labyrinth spiders (funnel web spiders) are a fun anomaly due to the complexity of their trap, which is 3D, but arguably it's a still a passive way to hunt.
My favorite would be the net-casting spider, which builds a tiny web that it holds, and then casts on its prey. The timing and coordination of that is mind blowing:
https://www.youtube.com/watch?v=QyRPrax9MJU&t=19s
What if it takes so much energy to move in the fourth dimension that the entities have to be vulnerable? They might be even easy to catch, or destroy by accident.
Not really the same but I've been doing paragliding since a long time, and my wing is definitely a giant sensor for 'air movements shape'. Kind of a part of me when in the sky.
Reminds me of the sci-fi book Children of Time. It follows the cultural evolution of a species of intelligent spiders. When they're angry, they vibrate and shake the web a certain way. In larger meetings, the spiders all share a single web, and private "whispers" are subtle plucking of private strands between two members.
If one enjoys reading SF that involves intelligent spiders, then A Deepness in the Sky [0] is worth a look. Although the arachnoids in 'Deepness' are spider-like aliens, rather than evolved Earth-spiders, as in Children of Time. The latter also has evolved ants, as well. Both books are highly recommended.
Maybe I missed it, but from the spider's perspective do we / can we know if sensing the web vibrations actually feels the same as hearing shorter-range sounds they could pick up naturally? Or is it possible they're just reacting to the web vibrations as more of a touch stimulus?
Since the web is much bigger than whatever serves as spider ears, it should pick up much lower frequencies, if my physics intuition is working this morning.
Is the spider's reaction to "hearing" a sound different than its reaction when an insect lands on the web? You'd expect it to react when the web vibrates.
I imagine if I were to set up a parabolic reflector, my reaction to sounds I hear would be different from my reaction of something hitting the reflector itself.
Spiders invert this relationship -- they are 2D specialists that slice a 3D space with a trap, capturing 3D specialists without expending energy to navigate their prey's space.
Not quite a free lunch -- it takes some prep work in the lifetime of a spider to survive. Losing your web makes you suspect to getting wrecked by robber flies until you build a new one.
On a more science fiction note, I've wondered about generalizing this 2D/3D existence relationship into humans interacting with a hyper-dimensional entity. Will we also have to evolve to build traps against the perception weaknesses of our 4-dimensional invaders?
Anyway, I've thought about the level of fidelity of information a spider could get from vibrations on a web. It's probably a function of nervous system ability and sensitivity for the spider to discern frequencies of forces impacted unto it by the web, as well as the frequencies filtered by the web itself. Looking forward to reading the paper.