Maybe that comparison is wrong, i.e. different kinds of energy compared for humans and earthworms? For the later, if I understand correctly, the linked paper measures an equivalent of "how much energy one gets by burning the stuff from which an earthworm is made". For the former, it's something else: "total stored charge in all mitochondria membranes".

I'd expect that comparing the same kinds of energy the ratio would be more similar to a ratio of weights of the two organisms.