When some species, including Bathyctena chuni, Euplokamis stationis and Eurhamphaea vexilligera, are disturbed, they produce secretions (ink) that luminesce at much the same wavelengths as their bodies.
When do bathyctena chuni, euplokamis stationis and eurhamphaea vexilligera  excrete secretions?
are disturbed,