ChEBI: Octopamine is a member of the class of phenylethanolamines that is phenol which is substituted at the para- position by a 2-amino-1-hydroxyethyl group. A biogenic phenylethanolamine which has been found to act as a neurotransmitter, neurohormone or neuromodulator in invertebrates. It has a role as a neurotransmitter. It is a member of phenylethanolamines and a member of tyramines. It is a conjugate base of an octopaminium.