The behavioural cue of ‘flexible self-protection’ is a way to establish whether an animal feels pain, scientists say
Crickets that received the hot probe “overwhelmingly” directed their attention to the affected antenna – they groomed it more frequently, and tended to it over a longer period of time, he says. “They weren’t just agitated and flustered. They were directing their attention to the actual antennae that was hit with this hot probe.”
Many insects don’t have a nervous system. Also, some plants respond to physical damage (albeit very differently than an animal) and they don’t have nervous systems, either.
It would also be possible to build a machine that can detect damage to itself and program it for self preservation, but that doesn’t intrinsically mean it would feel pain.
What insect doesn’t have a nervous system?