Why do some animals (like spiders or lizards) spend so much time just doing nothing? What is happening and why?
In: Biology
What’s the most energy efficient thing you can do?
Nothing.
If you’re not hungry, it’s not mating season, and there are no challengers for your territory… why do anything?
Reptiles and arthropods have taken a much different evolutionary path to success that relies on massive energy efficiency. They require very little energy and can thus live for a very long time without food and/or survive in poor environments.
Most organisms are in a constant struggle for energy. Obtaining energy is dangerous, you have to leave your save burrow or go risk injury in a hunt.
That’s why many organisms develop strategies for minimising the risks they need to take. And one of the most popular strategies is simply having simple, low demand physiologies, slow metabolisms and generally low energy needs.
Warm blooded animals are fairly unique. We’re like a car with the engine constantly running. That means we’re ready to go from zero to a 100 right away but we’re also guzzling gas constantly, even if we’re standing still. That’s why warm blooded animals need toc constantly eat. Some of the smaller more high energy creatures like humming birds can starve to death in a matter of hours.
By comparison, cold blooded animals waste zero energy on body heat. The downside is that they need to warm their bodies up with external heat like sunlight in order to get their digestive enzymes working or to get their muscles ready for fast action.
But on the upside, they need so little energy that they have to take far fewer risks than warm blooded animals. Some cold blooded animals can go up to a year or even longer without food.
Besides energy, lots of spiders and lizards are both predator AND prey. They have to balance foraging for food with avoiding predators that might eat them. They also have to balance mate attraction. Each species will have a different strategy.
In the case of lizards, they are cold blooded. They may appear to be doing nothing, but sitting and basking allows them to digest properly, among other things.
If you watch the TV show Alone where they have to survive with minimal food (what they find/kill) one of the most important skills is to do literally nothing and not go insane. It conserves calories. If they had a book or TV I’m sure they’d go for those, but they don’t so they just half nap do nothing.
Even 200 years ago (and many people today) humans spent vast amounts of time doing nothing. Things like farming were seasonal and required intense work at times and no work at others. When there was nothing to do, people often did nothing.
I was in rural Dominica and encountered a gent with no TV and I doubt he could read. He had a tiny little house and grew his own food. He’d usually be sitting outside doing absolutely nothing.
You often hear Europeans meeting indigenous people going on about how lazy/idle they were. It wasn’t because they were slackers, there was just nothing that needed to be done and doing other stuff was a waste of energy.
Cold blooded, can survive on a meal a month or so in a lot of cases.
There is just no reason to expend energy. You just wait for an opportunity to eat and then chill out.
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Humans are actually ~~very~~ somewhat unique in that they get bored at all. Look at lots of animals (especially cold blooded animals like others have said here) and you’ll see that they often spend a lot of time sleeping or just idly resting. I mean you can see that on any zoo trip.
They have evolved so that they don’t need to be doing stuff all the time to survive, so why waste the energy? As long as you can accomplish what you need to do to survive and reproduce, you’ve got your food, water, shelter, and territory… you’re good.
Humans are interesting in that we’ve developed very complex brains and behaviors to survive, AND since we’ve been so successful survival-wise, we have a lot of surplus energy to burn. We’re omnivores that are extremely adaptable, so to aid our survival, behaviors like exploring, keeping up with social bonds (and all the complex tasks and behaviors we do for that, like playing games and navigating social rules), hunting, gathering, farming, building, inventing tools, etc etc etc… all of those things had a purpose for us, so there was incentive for our brains to be thinking about doing stuff all the time and feeling a sense of reward for accomplishing those things. Since we established more organized societies and agriculture, food is usually in ready supply, so it’s okay to even “waste” that brain power on stuff like entertainment, science, philosophy, arts, whatever – which all has social benefits or benefit society in the long-term even if they don’t have immediate survival benefits – or in the case of entertainment, because we’re wired to feel rewarded for doing stuff.
TLDR If we were lizards, we probably wouldn’t find playing video games very rewarding because its a waste of time and energy. As humans we have the energy to burn and social/societal benefits for doing stuff all the time, so we get bored because we have the energy to be doing something rewarding.
Edit to address the replies: yes, other animals get bored too, it’s just something humans experience at a greater scale and we do more complicated stuff to entertain ourselves. Also, yes, humans do need time to do nothing as well – we’re not wired to spend 100% of our time doing stuff. It’s in fact very healthy to take time just to do nothing. Rest and mindfulness will do wonders for your mental health – we just live in a high-stimulation and productivity-obsessed society, so it can be hard sometimes.
Edit 2: to those getting pedantic in the replies about my first couple of sentences: this is ELI5. It’s an oversimplification.
Doing things consumes energy.
Imagine if you drove your car around all day every day; you’d need to put a **ton** of fuel in there to keep it going.
Same thing for living creatures. Creatures that are highly active (birds, rodents, etc.) eat an absolutely massive amount of food compared to their size. Some birds eat double their own body weight in food every day. Imagine a 150 pound human eating 300 pounds of food every day. That’s the price for moving around a lot.
So some animals go the opposite route. Move very little, eat very little. This works especially well for ambush predators like spiders. Make the web and then just wait. No use in burning excess energy. When something lands in the web, go eat it and wait some more.
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