They're probly like fuzzles, they're small but play an important role. Or they could be like fleeches, small but deadly.
Anyway, I know this isn't the best time to get all 'scientific-like' but I wouldn't call them spiders. Spiders are arachnids and to be an arachnid you must have two body segments and eight legs. This spider does have 2 body segments from what I can see, but it seems to have only four visible legs. But, seeing how it looks just like a spider I guess it's okay we can call it that for the time-being.
