Octopus

Is the octopus your favorite animal? If not, maybe it should be! Every time I learn more about them I like them more. (I read some books about octopuses when we did a big Animal Kingdom Unit a few years ago and my admiration for them has only grown since.)

Daisy and Junie have also already liked octopuses for a long time (they used to call out "Octo-pus!" as part of some chanting game they played and I never really knew why) and this unit redoubled their enthusiasm. Junie embarked on a mad crocheting spree, making the rainbow octopus (above), as well as her enormous chef d'œvre which she gave to Daisy for Christmas, Squiddy:'

(Don't be confused by Squiddy's name. He is still an octopus; his name is just Squiddy)

Junie also made this cute sea turtle

And Daisy started making tiny octopuses and couldn't stop. She made nine of these and put them onto little keychains for Junie and Goldie and all their ballet friends.

For school, we did all kinds of fun little demonstrations of some of the interesting things an octopus can do. For one thing, we pretended this Ziploc bag was an octopus (they have no bones, only a cartilaginous beak) and showed how it could therefore squeeze itself through a really tiny hole and fit into all kinds of tight spaces.

We observed how octopus "ink" can confuse a predator and allow the octopus to get away quickly in the water

And we learned about one of the most interesting abilities of an octopus, its ability to change color and texture almost instantly. (See here, for example.) They do this using their specialized chromatophore, iridophore, and leucophore cells. (Sam drew me this octopus.) Basically, they can contract the muscles controlling each type of cell to display more or less of that cell's characteristics. We did this demonstration (idea found here) to show how that works:

The little umbrellas represent the different types of cells. Each expresses a different color. All of them are present in the skin all the time, but when some are relaxed (or contracted, I'm not actually sure which process allows them to expand), they spread out and create the appearance of that color over the whole body. (Here, we see the octopus looking red.) (And of course the cells are actually crowded so much closer together in a real octopus!)

Here, we can see that the red chromatophores have been contracted again and the green chromatophores are relaxed, making the octopus now appear green! You can also imagine how many variations would be possible when only some of each color of cells are opened or contracted, or when colors are combined with the textural and reflective variants in the other cells! So amazing!

Some interesting octopus videos (but you can find so many more):

https://thekidshouldseethis.com/post/can-squids-fly-ted-ed-video
https://www.youtube.com/watch?v=7__r4FVj-EI octopus maze 
https://www.youtube.com/watch?v=MSAtmyLKmG4 color changing
https://www.youtube.com/watch?v=zEXUOPkQPo8 octopus nursery
Secrets of the Octopus documentary (Hulu)

My Octopus Teacher documentary (Netflix—we watched this one last time we studied octopuses)