“…Many bioamine neurotransmitters, such as 5-HT, dopamine, adrenaline, and noradrenaline, have been identified in different tissues of echinoderms using biochemical and histochemical methods [21,44,109,110]. These neurotransmitters are involved in regulating a variety of physiological behaviors in echinoderms, including reproduction, ovarian maturation, embryonic development, morphogenesis, settlement, and swimming behavior [21,93,[110][111][112][113]. At the same time, the effects of numerous bioamines on various echinoderm muscles have been examined, and their functional characteristics are highly variable [21,86].…”