New Scientist takes a surprisingly nuanced look at the way things like oysters and shrimp might actually be responding to trauma. They’re not all the same. Research shows that, as much as we want a guilt-free crab boil, invertebrates do feel pain… some of them:
Unlike crustaceans, insects seem to have no pain-related behaviours. If an insect’s leg is damaged, for example, it does not groom or try to protect the limb afterwards. Even in extreme cases, insects show no evidence of pain. Imagine a praying mantis eating a locust, says Smid. With its abdomen opened up, the locust will still feed even while being fed on itself.