First thing to note is that "worthy of moral consideration" is plausibly a scalar. The philosophical & scientific challenges involved in defining it are formidable, but in my books it has something to do with to what extent a non-human animal experiences suffering. So I am much less concerned with hurting a mosquito than a gorilla, because I suspect mosquitoes do not experience much of anything, but I suspect gorillas do.

Although I think ability to suffer is correlated with intelligence, it's difficult to know whether it scales with intelligence in a simple way. Sure, a gorilla is better than a mouse at problem-solving, but that doesn't make it obvious that it suffers more.

Consider the presumed evolutionary functional purpose of suffering, as a motivator for action. Assuming the experience of suffering does not require very advanced cognitive architecture, why would a mouse necessarily experience vastly less suffering that a more intelligent gorilla? It needs the motivation just as much.

To sum up, I have a preference for creatures that can experience suffering to not suffer gratuitously, as I suspect that many do (although the detailed philosophy behind this suspicion is muddy to say the least). Thus, utilitarian veganism, and also the unsolved problem of what the hell to do about the "Darwinian holocaust."