Do hermit crabs eat small spiders?

Answer 1

Not usually. They should be the same size, and eat or harm each other when threatened. If your crabs seem aggressive, separate them. If they fight over food, feed them separately. That should solve the problem!

Answer 2

Yes, they do. That is they're favorite snack, and meal! But to get back on topic, they do eat small Spiders quite often, when I saw some hermit crabs at the beach once, they had like 12ish dead spiders around them that they were ready to eat.