r/todayilearned • u/koreanforrabbit • 16h ago

TIL the ridges in a cactus are actually pleats which expand as water is taken in. They contract to decrease exposed surface area during droughts, which reduces water loss.

https://youtu.be/bx9x4F7_bzA?is=iehcZdcafY8-wR1B
138 Upvotes

94% Upvoted

9 comments sorted by

30

u/the_mellojoe 16h ago

have you seen the inside of a cactus? They have bones. long vertical semi-rigid wooden ribs that give it structure, but can also expand and contract depending on water intake. a large saguaro cactus can weight multiple tons, so these bones give it strength to hold itself up.

19

u/koreanforrabbit 16h ago edited 16h ago

Ok, I teach Kindergarten and have been writing up my plan to teach this to the kids tomorrow during my daily "Fun Fact About ______". And now, you, my dawg, have just added a dissection activity. Thank you!!!

Also, my job is really weird and fun.

Edit: Not a saguaro. Can you imagine??? Just a little window baby succulent and a Home Depot cactus. They're five years old - it's more about the process than the findings. 😎

8

u/the_mellojoe 15h ago

Heh. I assumed not a saguaro. That would be illegal, as they are protected, I think. :D

Here's another fun saguaro cactus fact: they are OLD. Very very old. It takes over 40 years for a baby saguaro to grow its FIRST arm. Those ones you see in pictures with 4 and 5 arms? We're talking well over 100 years old. Often 150 years old.

https://imgur.com/a/1vRVcNG

3

u/Holiday_Ad_9163 7h ago

I have seen inside a cactus and it definitely didn’t have wooden bones. Maybe it’s a different king of cactus?

1

u/the_mellojoe 5h ago

True. There are many different types of cactus. I was specifically speaking of the saguaro. They fascinate me. And have for the past 15 years or so that I’ve lived in Arizona. They are giant.

2

u/Holiday_Ad_9163 4h ago

Oh yeah neat. I just looked up some photos of ancient ones that have died and are just like a bundle of wood stalks inside. I guess that makes sense how they can get so big. Pretty cool

3

u/z8_GND_5296 14h ago

unavailable in my country? Fuck you PBS!

3

u/Green-Cricket-8525 10h ago

Yeah, it’s kind of lame that PBS content is region locked sometimes. You might try finding the video on their actual website.