The researcher has identified a muscarinic acetylcholine receptor (mAChR) in the iridocytes and leucophores of Doryteuthis opalescens that is hypothesized to control dynamic camouflage. A sequence alignment showed 49% identity between the squid and human mAChR. Key residues in the acetylcholine binding pocket are conserved. Transcripts for downstream signaling proteins Gαq, PLC-β4, and CALM were found in iridocytes but not leucophores. Identifying the mAChR receptor sequence will allow future study of its role and location in color change.