Caenorhabditis elegans
Neurons functionally specialized for nociception have been documented in other invertebrates including the leech "Hirudo medicinalis", the nematode "Caenorhabditis elegans" and the molluscs "Aplysia californica" and "Cepaea nemoralis". Changes in neuronal activity induced by noxious stimuli have been recorded in the nervous centres of "Caenorhabditis elegans", "Drosophila melanogaster" and larval "Manduca sexta".