File:Novel-Insights-into-the-Echinoderm-Nervous-System-from-Histaminergic-and-FMRFaminergic-Like-Cells-pone.0044220.s002.ogv

English: Experimental recording of the same two adult L. clarki in a divided petri dish filled with sea water. After the control recording, one animal (on the left) was injected with a volume of histamine that upon dilution in the body cavity would approximate a 200 µM concentration and the other animal (on the right) was injected with the same volume of filtered seawater. Injection of histamine (on the left) clearly increases the frequency of anterior-to-posterior peristaltic contractions. Blind scoring of additional trials on different animals showed that this histamine-induced change in the direction of peristaltic contraction is highly repeatable (see Fig. 7).