“…Sponges lack true organs, muscles (Pavans de Ceccatty, 1986, 1989) and a nervous system (Jones, 1962;Pavans de Ceccatty, 1974), but they nevertheless possess coordinated contractile behavior as a response to external (Elliott and Leys, 2007) and internal stimuli (Reiswig, 1971a). This behavior includes contraction and inflation of the sponge body as well as the inhalant (ostia) and exhalant (oscula) openings (Prosser et al, 1962;Reiswig, 1971a;Gaino et al, 1991;Nickel et al, 2006;Elliott and Leys, 2007;Strehlow et al, 2016). As a possible consequence of their contractile behavior (Reiswig, 1971a), sponges arrest their pumping activity in regular as well as irregular intervals with time scales ranging from minutes to several days (Patterson et al, 1997;Tompkins-MacDonald and Leys, 2008;McMurray et al, 2014).…”