title: Development of swimming behaviour in the larva of the ascidian Ciona intestinalis.
abstract: The aim of this study was to characterize the swimming behaviour of C. intestinalis larvae during the first 6 h after hatching by measuring tail muscle field potentials. This recording method allowed a quantitative description of the responses of the larva under light and dark conditions. Three different larval movements were distinguished by their specific frequencies: tail flicks, 'spontaneous' swimming, and shadow response, or dark induced activity, with respective mean frequencies of about 10, 22 and 32 Hz. The shadow response develops at about 1.5 h post hatching (h.p.h.). The frequency of muscle potentials associated with this behaviour became higher than those of spontaneous swimming activity, shifting from 20 to 30 Hz, but only from about 2 h.p.h. onwards. Swimming rate was influenced positively for about 25 s after the beginning of the shadow response. Comparison of swimming activity at three different larval ages (0-2, 2-4 and 4-6 h.p.h.) showed that Ciona larvae swim for longer periods and more frequently during the first hours after hatching. Our results provide a starting point for future studies that aim to characterize the nervous control of ascidian locomotion, in wild-type or mutant larvae.
authors.affiliation: Neurobiology Laboratory Stazione Zoologica Anton Dohrn, Villa Comunale I-80121 Naples, Italy. giuliana.zega@unimi.it
authors.forename: Giuliana
authors.initials: G
authors.lastname: Zega
authors.forename: Michael C
authors.initials: MC
authors.lastname: Thorndyke
authors.forename: Euan R
authors.initials: ER
authors.lastname: Brown
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000704:Analysis of Variance; D000818:Animals; D002938:Ciona intestinalis / Q000502:physiology*; D007558:Italy; D007814:Larva / Q000502:physiology; D008027:Light; D018482:Muscle, Skeletal / Q000502:physiology*; D013550:Swimming / Q000502:physiology*; D013623:Tail / Q000502:physiology*