Calcitonin (CT) and CT gene-related peptide (CGRP) are well known to regulate blood calcium concentration and osmotic pressure in vertebrates. Although lophotrochozoan CT-like peptides and their receptors have been characterized in several model species, the presence of CT-like signaling systems in gastropods remains unknown. In this study, we identified two CT-like peptides, Hdh-CT1 and -CT2, and their receptors (CTRs), namely Hdh-CTR-L and -CTR-S, in Pacific abalone. Transcripts encoding Hdh-CT1 and Hdh-CT2 precursors were expressed mainly in neural ganglia. Molluscan CT-type peptides including Hdh-CT peptides were similar in length and showed highly conserved two Cys residues forming a disulfide bond in their N-terminal regions. A phylogenetic analysis revealed that gastropod CTRs, including Hdh-CTRs, belong to a large molluscan CTR subfamily. A luciferase reporter driven by cAMP responsive element was stimulated by Hdh-CT1 but not by Hdh-CT2 in Hdh-CTR-L-transfected human embryonic kidney 293 cells. In silico docking model using SWISS-MODEL and HPEPDOCK server showed that the N-terminal residues in Hdh-CT1 are deeply inserted into the binding pocket of Hdh-CTR-L. Taken together, the identification of the Hdh-CT system provides a comprehensive insight into the functional CT-type signaling system in marine gastropods.