title: Larval vision contributes to gregarious settlement in barnacles: adult red fluorescence as a possible visual signal.
abstract: Gregarious settlement, an essential behavior for many barnacle species that can only reproduce by mating with a nearby barnacle, has long been thought to rely on larval ability to recognize chemical signals from conspecifics during settlement. However, the cyprid, the settlement stage larva in barnacles, has one pair of compound eyes that appear only at the late nauplius VI and cyprid stages, but the function(s) of these eyes remains unknown. Here we show that cyprids of the intertidal barnacle Balanus (=Amphibalanus) amphitrite can locate adult barnacles even in the absence of chemical cues, and prefer to settle around them probably via larval sense of vision. We also show that the cyprids can discriminate color and preferred to settle on red surfaces. Moreover, we found that shells of adult B. amphitrite emit red auto-fluorescence and the adult extracts with the fluorescence as a visual signal attracted cyprid larvae to settle around it. We propose that the perception of specific visual signals can be involved in behavior of zooplankton including marine invertebrate larvae, and that barnacle auto-fluorescence may be a specific signal involved in gregarious larval settlement.
authors.affiliation: KAUST Global Collaborative Research Program, Division of Life Science, The Hong Kong University of Science and Technology, Hong Kong.
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Matsumura
authors.forename: Pei-Yuan
authors.initials: PY
authors.lastname: Qian
mesh_terms: D000819:Animal Communication; D000818:Animals; D054910:Compound Eye, Arthropod / Q000502:physiology*; D005453:Fluorescence; D007814:Larva / Q000502:physiology; D001468:Thoracica / Q000254:growth & development / Q000502:physiology*; D014796:Visual Perception
keywords: Auto-fluorescence; Balanus amphitrite; Barnacle; Compound eyes; Cyprid larva; Gregarious settlement; Larval sense of vision; Larval settlement; Settlement cue; Surface color; Visual signal; Zooplankton