Do Black Tentacles “protect” you from ranged attacks as creatures grappling you do?

If you are trying to shoot some creature, and your target is grappling, rules say: "roll randomly to see which grappling combatant you strike".

Does Black Tentacles spell’s effect count as a combatant? Or should you just roll high enough attack to strike a creature, grappled by Tentacles, as there is no actual target other then the creature you are aiming at?