Get off it! People who have a passion for something seek it out. If the kid loves animals he's going to want to learn about them and be around them.
If you are of the opinion that the spider is deserving of the same rights people have then I'd like to hear the spider make the argument. We, as humans, have the rights we have because we have the capacity to understand them and the desire to assert them. The spider is not in the same weight-class and doesn't enjoy the same benefits.
Are lions cruel to gazelles when they crush their throats and suffocate them to death? No. Why? Because they must eat gazelles to live and they don't have the capacity to empathize with the gazelle. It is only us, the greatest species in known existence, that can empathize with the suffering of other animals. It is only us who has the capacity to be either kind or cruel. Only we have the ability to choose. The lion isn't weighing the gazelles suffering against it's own hunger. The gazelle doesn't get the slightest bit of consideration from the lion. The lion completely lacks the ability to give a **** about the gazelle and any suffering it might endure.
Humans win. Every time.