The co-ordination of the protective retraction of coral polyps

摘要: The responses to electrical stimulation of a number alcyonarian, zoanthid and madreporarian corals are described. All groups studied except gorgonids show extensive coordination over the colony. In Sarcophyton (Alcyonacea) response is typically local at first but eventually wave polyp retraction can be made spread astraeid alcyonarian Tubipora have whole colony through-conducting system which has refractory neuromuscular properties similar those found in mesenteries actinians. Palythoa successive shocks produce excitation spreads progressively farther across each shock for as many fifty two-second intervals. perforate , Acropora, Goniopora Porites respond single by co-ordinated polyps. Except Acropora it characteristic that one point never no matter how stimuli applied. individual polyps corals, including Fungia described, all there similarity column, disk tentacle already known actinians, e.g. Calliactis . concept interneural facilitation been analyzed use working model shows simple theory inadequate an explanation transmission between certain species because predicted distances either too variable or small compared with actual observed stimulus animal. co-ordinating systems various considered variations on common theme, conduction units form network. stages from poor co-ordination, through progressive stimulus, condition interpreted reflexion increasing probability all-or-nothing unit pathway next population large units, only proportion may active any time. neurones, probable parts polyp, regions such within normally through-conduction stimulus.