Does USB still draw current even with external power source removed?

I set up a row of external drives - all with external power sources (mybook, easystore) and ALL western digital!
All of the power cords - with transformers are plugged into a power strip with individual on/off switches for each drive. All of the USB cords run into a hub.

I just saw a hub with individual on/off switches for each port and started wondering if i should grab one. I know there won’t be any transferring of data with the power strip switch off.

BUT… can it still draw power off the computer? Is it worthwhile to grab a USB hub with switches to save on electricity? Any other considerations i may have missed?

EDIT - sorry i forgot - ALSO - is there a difference in adaptors? I have a bunch of drives from 8Tb to 16Tb. Most of them are two pronged and come off the “side” of the plug outlet. The two biggest drives however drop down off the plug outlet. Is this to signify a different current/voltage (i cant read the tiny writing on them to see myself) or are they all the same specs just different design? Thanks

If you plug an unpowered external usb drive then computer is supplying power to usb port to power the external drive. (5V 900mA)

If you plug a powered external usb drive then the AC Adapter is supplying the power to the external drive. (12V 1.5A ~ and higher)

So, a usb hub with individual power switches will not make any difference to the power consumption of a powered external hard drive because the AC Adapter is supplying power to drive … even with the usb hub switch on or off .

The power switch on the usb hub will of benefit only when using non-powered usb external drives.

If you want to save on electricity, then switch off the powered external hard drive at wall or power strip where the AC Adapter is plugged in.

Power adapter design can change and does not signify the voltage and current rating.

The voltage and current rating is on the label of the adapter … if you can’t read it, then use a magnifying glass or eye glasses or macro zoom on a camera or smartpone.