Jellyfish are among the most phylogenetically distant animals from vertebrates, raising fundamental questions about their capacity for pain, suffering, and welfare-relevant experience that science is only beginning to address.
The welfare relevance of jellyfish remains scientifically uncertain. Without a centralised nervous system, complex pain processing as seen in vertebrates seems unlikely, but nociceptive responses are present. The precautionary principle suggests avoiding causing unnecessary harm even to animals with uncertain sentience. Jellyfish strandings, entanglement in marine debris, and physical damage from boat strikes are common causes of injury. Some researchers argue that even primitive nociception warrants moral consideration.