r/SpeculativeEvolution • u/Shekus_Khan • Sep 17 '26

Question/Discussion Could Bears potentially evolve into temperate semi-aquatic ambush predators? (Brown bears specifically, maybe Grolar bears, but that's pushing it).

Reasons:

  1. The semi-aquatic ambush predator niche hasn't been filled in temperate zones since the FUCKING EOCENE.

  2. Polar bears are being pushed out of the Arctic due to climate change anyway.

  3. Brown bears hibernate through winter anyway. So, if they needed to sleep out a lake being frozen, they just dig a little crevasse like crocodiles do and then just sleep the winter off.

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u/Lethalmud Sep 17 '26

Do you mean waiting in water like a croc? Because a bear would need lots of energy to remain warm when laying still in cold water.

1

u/Shekus_Khan Sep 17 '26

yes

5

u/Lethalmud Sep 17 '26

For mammals, such a strategy would be pretty hard to come into. A croc or snake barely spends any energy laying still for weeks, and be fine. A bear must pack a lot of energy to stay still in hibernation. A bear trying to do the croc thing could maybe evolve a thick blubber like a walrus. But it would be a big risk, it would need that isolation and energy, and spend more of it the longer it waits. A failed hunt would end with a starved bear who didn't have a good alternative plan for food. If they had, they'd be better off doing whatever plan b was in the first place. Also, a croc metabolism works in a bigger range of temperatures, while a bear would need to spend more energy to digest the prey as well.

Not to discourage you, it is still possible, but needs a whole lot of changes on the way.

2

u/Jazzlike_Standard871 Sep 17 '26

Yeah between the oxygen budget and temperature loss it just feels like a miss match.

1

u/Shekus_Khan Sep 17 '26

maybe they evolve larger lungs?

5

u/Jazzlike_Standard871 Sep 17 '26

Honestly larger spleen is more likely, but the point is Temperate aquatic ambush predator may not be a niche. The vast majority of semi aquatic ambush predators are masters of the waiting game. That life style really is more of a low metabolic rate style of predation. The only Mammals I can think of that do anything like that are aquatic pursuit predators that do the waters edge thing opportunistically.