"Even if the probability of arthropods being sentient is considered much lower (e.g. less than 10%), the precautionary principle should be applied, because there are huge numbers of arthropods. At this moment, there are about 1018 terrestrial arthropods (mostly ants) and 1020 marine arthropods (mostly very small copepods as zooplankton). This can be compared with about 1010 humans. So if arthropods happen to be sentient and we erroneously believe they are not, we are neglecting huge amounts of welfare and suffering. When a lot is at stake, the precautionary principle is reasonable."