Invertebrate animals are frequently lumped into a single category and denied welfare protections despite their considerable cognitive, behavioral, and evolutionary diversity. Some ethical and policy inroads have been made for cephalopod molluscs and crustaceans, but the vast majority of arthropods, including the insects, remain excluded from moral consideration. We argue that this exclusion is unwarranted given the existing evidence and plausible concepts of moral standing. Yet anachronistic, value-laden readings of evolution still view invertebrates as lower in the scala naturae. There persists the a priori assumption that small brains are unlikely to support cognition or sentience, despite the growing evidence that they have converged on cognitive functions comparable to those of vertebrates. Cognitive-affective biases influence moral judgments and the attribution of mental states. Scientific uncertainty and moral risk are not appropriately balanced. These factors shape moral attitudes toward basal vertebrates too, but they are particularly acute in the arthropod context. Moral consistency dictates that the same standards of evidence and risk management that justify policy protections for vertebrates also support extending moral consideration to certain invertebrates. We also show how moving beyond a vertebrate-centered concept of welfare can help clarify foundational moral concepts in their own right.