The luminescence of lanternfish (myctophidae): Spontaneous activity and responses to mechanical, electrical, and chemical stimulation

Abstract

Spatial and temporal aspects of luminous responses in several common species of Southern California lanternfish (Myctophidae) were analyzed using T.V. image intensifier and photomultiplier techniques. The two principal types of luminous tissue, photophores and luminous tissue patches, responded in strikingly and consistently different ways to both mechanical and electrical stimulation. While typically producing a variable intensity glow spontaneously, the entire photophore array proved capable of coordinated, simultaneous activation by electrical stimulation. Although never active in undisturbed shipboard animals, luminous tissue patches, primarily, supra- and infracaudal organs, produced brilliant, rapid, transient displays to both mechanical and electrical stimulation. Light from the supra- and infracaudal organs is produced by 3–9 visually distinct subunits capable of both simultaneous and temporally variable activation. Electrical excitation gave maximum response rates of up to 30 flashes/sec in the luminous patches of all the species tested, whether tissue was from caudal organs or ventral or supraorbital patches. Chemical stimulation never triggered luminous responses from luminous tissue patches, and gave only ambiguous results with photophores. The results are discussed in terms of effector control and functional potential of the various luminous displays.