Whether animals are sentient beings is a question that scientists have been puzzling over for centuries.
Some cognitive experts would argue that there are varying levels of consciousness for different living things, or that some animals may have an emotional capacity while others may not. Dog owners will certainly argue that their pets have emotions but it is less certain if plants, insects and fish have feelings too, as we cannot see them express any. As fish have a simpler brain structure than mammals, they lack a cerebral cortex, which could mean that they lack the ability to feel suffering and pain. However, a 2015 study published by The Royal Society showed for the first time that zebrafish experienced something called ‘emotional fever’ (stress-induced hyperthermia, which was believed to happen to mammals, birds and reptiles only). Zebrafish subjected to a short period of confinement experienced a rise in body temperature of 2-4°C, showing the capacity to respond to stressors. There’s a lot of scientific interest in this area so studies and debate over whether fish experience emotion continue.
