bat opens up their little bat wallet to find they are all out of moths. A worthless $100 bill flies out for emphasis
From top-of-frame, a month flutters into the wallet. Confused, the bat looks "up" to see an equally-confused human standing "above" her, holding an open wallet containing a single $100 bill.
Camera rotates to reveal bat has been hanging upside down above a human doing the exact same visual gag and each ruined the other's bit.
Laugh track.
I still can't fucking get over how cetaceans adapted to spend their entire lives in the water and just never bothered to redevelop water-breathing. there's motherfuckers who spend an hour or more diving and the evolutionary solution is just "breathe a lot on the surface and then lower your heart rate to a near-hibernation level while actively cruising the seafloor for stuff to eat". totally insane solution to one of the oldest solved problems in biology
Well, there are some good reasons for that.
First, foremost, and Steve Alten be damned, one cannot simply "re-evolve" gills. All the bits and bobs that used to be gills in our water-breathing ancestors are jaw and ear bones now. If some kinda mammal wanted to reacquire the ability to breathe water, it'd have to be from scratch. Evolution is a cheap-ass, so as long as there's a perfectly good set of lungs on that fella, it's not gonna bother to make an entirely new lung-alternative.
Secondly - and psych, this is actually more important - compared to air, water fukken sucks as an oxygen carrier! At its highest, water's potential for holding dissolved oxygen maxes out at 14.6mg/L...for fresh water...at 0°C. Saltwater carries about 7-8mg/L of dissolved oxygen. Good ol' air, meanwhile, holds a whopping 21mg/L of oxygen! Compared to water, that's pure jet fuel! It's just more efficient to go up to the surface for a breath of air and hold it.
TL;DR, mammals don't have the tools to evolve the ability to breathe water and no incentive to do so in the first place.
its weird to me that dolphins and great white sharks have like, not totally dissimilar sizes and speeds when they're getting the oxygen for those muscles in a completely different way.
Drag, I guess.
Yeah: Sharks are just so smooth that, even with the more inefficient breathing method, they can still maintain similar speeds and sizes u_u u_u
would brains work less efficiently if they were made with similar structure but made of something more rigid?
Well, that’s basically what electronics are in a sense, a brain made of rigid materials, and plant cells, which are housed in rigid walls, engage in constant communication with one another.
I see no reason why a hypothetical organism couldn’t have a “hard” brain. It wouldn’t be made of brain cells exactly like ours but as long as it can pack a lot of them in its body, supply them with a lot of energy, replace them at a consistent rate and easily distribute signals among them it should work.
Efficiency isn’t the issue – far from it, in fact! Electrical neurons work by generating a constant low-level electrical imbalance in their membranes (usually around 40 mV, but that’s not always so), then neutralizing that imbalance in what’s called an “action potential.”
This depolarization cascades down the axon, gets pooped into another neuron by chemicals, and continues until it hits something that can deal with it. Having a brain made out of something that doesn’t slosh or jiggle around would make AP transmission a lot quicker and easier.
No, the big BIG problem with having a rigid brain would be growth and maintenance. Brains are mooshy b/c they’re basically electric fat, made of cells, so growth by cell-division and repair by eating the old stuff and making new stuff is pretty much easycakes McGee. However, when you try to substitute mooshy cellular tissue for something rigid, the energy requirements for growth and the difficulty of eating broken stuff goes crazy.
A good example is bone: bones aren’t made of cells. Rather, they’re made of rubbery connective proteins that are reinforced by metal phosphate struts. Since they need to withstand impact, these struts are very strong, but your bones need whole swarms of acid-belching, metal-phosphate-pooping worker cells to reshape them as you go about life, repair them if they break, and grow more if you’re a kid. The process of bone growth takes ages, and hurts the whole time.
Now imagine doing that, but instead of a simple rod, you’re weaving your rigid structure into an electrically conductive network capable of supporting consciousness and billions of years of redundant junk programming. At that scale and order of structural complexity, the process would take FAR longer than the 9 months it takes a regular person’s brain to grow, upkeep would be a nightmare, and a slight tap to the casing would shatter your brain to pieces – something that a mooshy meat-brain can take with comparatively few ill effects.
tl;dr, meat-brain better than bone-brain for living systems
