Questions on Raspberry and Blackberry bushes...

I planted raspberries and blackberries that i bought from Lowes or Home Depot. I was hoping for shrubs like my blueberries have grown, and yet these plants have grown "tentacles" like an octopus. I was hoping to not have to set up a trellis or arbor. Is this how they all grow? or only certain types. I really just wanted some shrubs...I threw some pvc pipe up behind them for now, the blackberries have recently been relocated. I havent had the money nor do i have the interest really in building more proper trellises unless i have to. Advice? Suggestions?

Raspberries and blackberries both grow canes, and the canes only bear fruit for a year. Before being cut, or dying back.

Raspberry canes will benefit from being tied to a wire at about 3ft high, but it is not essential if you don't mind a floppy plant. Your second year growth will likely be more robust and vertical,

Blackberry canes can be pruned back to around 3ft, and they will branch and make more fruit as a result. Again, they don't need tying in, but it can help keep them tidy.

In both cases, stems that have had fruit should be cut down to the ground in the winter and new canes will grow in.

So basically they arent your typical shrubs... would they benefit from a trellis system like i set up for my grapes?

What's worked best for me is to imagine a row of black/raspberries as a line 6-8" wide, basically put posts at the corners of that 8" x X' rectangle and run 3 or 4 levels of wire. Then you just train canes up between those wires, cutting anything that can't be trained into that column. And it's pretty easy to cut out the older canes

Have you considered planting the blackberry canes along that fenceline?  

That will save money and give them a nice sturdy place to climb and spread.  As an added function, it can add a little extra privacy (especially if it's a thorned variety) while softening the fence's texture.

So if you are looking for future bumper crops of berries, consider letting the canes grow toward the fence (or transplant them right by it), and then serpentine-layer them up and down all along the fenceline.  Wherever the cane touches the ground, add a bit of compost, dirt, and mulch, and a new bush will grow from there.

https://irrecenvhort.ifas.ufl.edu/plant-prop-glossary/images/08-layering/layeringserpentine/image1.jpeg