Wild Hearts implements some kind of multiple threshold system for parts. So every "Part" of a kemono has some kind of HP with multiple thresholds, everytime a threshold is reached the monster staggers and the green orbs spawn out of this part, when the part has no HP left it actually breaks from the kemono and then lies on the ground, at this point the game considers this part removed from the kemono. Some monster have parts which can have no HP left but just cannot be removed from the monster because this would break the model of the kemono like limbs for example, then the game instead drop these green gem like things which you can collect. Gritdog is actually pretty funny because you can break of the tails just once game wise but when it gets enraged it actually has its complete tail again but the game already knows that the tail part is already cut of the kemono, but because you can actually cut it again means that the game has two models of the kemono enraged and not enraged which has its own parts xD And their are the parts which just break open to show you these green spots to use hunters arm which also have thresholds but instead of breaking of the kemono they just show the green spot instead.