These buttons allow you to rise and dive the Cyclops. If you're driving the Cyclops at full normal speed, you don't need to worry because you're going so fast youl'll smash the little bastards against the hull. To actually go up and down in the Cyclops, you must use the Spacebar and C key for PC, the left and right bumper on the Xbox controllers, and the R1 and L1 buttons on the PlayStation 4 controller. You'll hear a little screachy type noise if they do and you can just hop out real quick and knife them 3 times and kill them. You also need to be aware that they can and will sometimes attach to your Prawn while you're out and about.

I used this technique a while ago when I was mining for Kyanite and it worked perfectly.

They can't suck energy off something that doesn't have any! You'll have to be quick while inside since without power, the Cyclops won't generate oxygen but you can still launch the Prawn/Seamoth from the bay after you remove the cells (although you can't re-dock until you put the power cells back in). Upgrade Modules are software drives that improve the Cyclops, Seamoth, Prawn Suit, and Scanner Room. If you plan on going out and exploring or drilling in your Prawn, etc, then the best solution I found is to simply remove all the power cells before you depart. If you are currently driving the Cyclops and they cling onto your ship, you can zap them off by cycling your shields. HOWEVER, you need to be careful if you're near the inactive lava zone since there are tons of those stupid lava larvae eeches that will latch onto your hull and drain your ship dry. The Cyclops will not lose power if the engine is off and you aren't doing anything like fabricating or it's charging a Prawn/Seamoth in the bay.

Subnautica how to use cyclops