This is a wonderful example of advanced Cinema 4D character rigging by Clement Vaucelle of Wipix, which uses xpresso and custom coding (the "secret sauce" of character animation):  

​https://vimeo.com/302309686?embedded=false&source=vimeo_logo&owner=2845272

​This is a great tutorial on the memory delay effect, which can tweaked for use in controlling an IK Spline:

​https://www.youtube.com/watch?v=l-5_lCKqJao

In March of 2017 I posted about Bill Melendez, an animator who ran the company responsible for producing, among many other things, the holiday classic "A Charlie Brown Christmas." Melendez was a key player in the Disney animation strike of 1941, which eventually led to the creation of cartoonists union Local 839 IATSE. 

So it's heartening to see a new generation of voices rallying behind the creation of a VFX union. VFX animators often work in incredibly stressed environments filled with impossible deadlines and last minute changes, things easily addressed with the establishment of ground rules limiting work hours and studio second-guessing of effects shots.  The following articles make for great reads:

https://gizmodo.com/disney-marvel-movies-vfx-industry-nightmare-1849385834

https://www.polygon.com/23291038/she-hulk-creators-disney-vfx-union

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Special thanks to Audrey Wong, Principal Technical Artist, Pixar Animation Studios, for providing this link to a technical paper authored by Theodore Kim, Fernando de Goes, and Hayley Iben, describing technologies used to create Hank the octopus in "Finding Dory." Some of these technologies were later incorporated into SideFX's Houdini software and Vellum. Unlike Cinema 4D, which uses quadrangles and N-gons, Houdini employs tetrahedrons to create meshes. 

https://graphics.pixar.com/library/AnisotropicElasticitySIGGRAPH2019/paper.pdf
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A test animation of one tentacle, using dynamics. 

The arms have been welded on. A tedious task, since it involves vertices on all eight arms, but no more tedious than dealing with suckers. 

The first rigged arm was cloned in mograph. Using Current State to Object, seven duplicates were made. Each "shoulder" has ten vertices that match the ten vertices at the end of each arm, so welding the points together should go relatively smoothly. Suckers crossed.

I'm correcting and tweaking the mesh prior to rigging. Here I've placed the head and shoulders portion in a cloth surface to give the model thickness. From there I used the Fit Circle command to make eight individual circular edges so I can connect the tentacles to what is now the body. And for those who got this far in the post and are thinking about lunch or dinner choices, I recommend the Margherita pie at Joe's Pizza in Santa Monica and West Hollywood. It has a sweet flavor and is arguably the best pizza in Los Angeles. Just saying.

Creating a vertex map to keep the suckers from deforming when zremesher is applied.