The Pearl begins with a defenseless baby getting stung irrationally by a poisonous scorpion. Symbolic? Let’s start with "defenseless baby." This arbitrary act of destruction ends up mirroring Kino’s tragic tale, which means Kino is on par with the innocent babe. The colonizing Europeans have intentionally kept Kino and the other natives in ignorance. Chapter Three even tells us that the doctor considers them children and treats them that way. If Kino is helpless to struggle against the injustice done to him, it is in part because of this ignorance: he doesn’t know how much the pearl should be worth, he doesn’t know that the doctor scammed him, that the priest is just as self-serving. He may have inclinations, but he’s still taking shots in the dark. In the same way, Coyotito is at the mercy of the scorpion.
Moving on from "defenseless baby." Next up, "stung irrationally." That Coyotito is poisoned is arbitrary. It is senseless, and it reflects a complete lack of divine justice in the universe. The gods are clearly not looking out anyone (just as Kino notes "the detachment of God" while watching an ant get buried alive in the sand). In this way, the finding of the pearl is equally arbitrary, as is Coyotito’s eventual death.
Next in our symbolic trio is "a poisonous scorpion." The whole scorpion bit comes not-so-subtly back up in the following passage from Chapter Three: "The news stirred up something infinitely black and evil in the town; the black distillate was like the scorpion, or like hunger in the smell of food, or like loneliness when love is withheld. The poison sacs of the town began to manufacture venom, and the town swelled and puffed with the pressure of it."
Well, take a look at that. Steinbeck doesn’t leave much to the imagination – the townspeople threaten Kino the same way the scorpion threatened his baby. Additionally, it seems like all the men –including Kino – quickly degenerate into animals, reduced by their greed and jealousy to their most base, primitive forms.