Dosidicus gigas (Humboldt or jumbo flying squid) is an economically and ecologically influential species, yet little is known about its natural behaviors because of difficulties in studying this active predator in its oceanic environment. By using an animal-borne video package, National Geographic's Crittercam, we were able to observe natural behaviors in free-swimming D. gigas in the Gulf of California with a focus on color-generating (chromogenic) behaviors. We documented two dynamic displays without artificial lighting at depths of up to 70 m. One dynamic pattern, termed ‘flashing' is characterized by a global oscillation (2–4 Hz) of body color between white and red. Flashing was almost always observed when other squid were visible in the video frame, and this behavior presumably represents intraspecific signaling. Amplitude and frequency of flashing can be modulated, and the phase relationship with another squid can also be rapidly altered. Another dynamic display termed ‘flickering’ was observed whenever flashing was not occurring. This behavior is characterized by irregular wave-like activity in neighboring patches of chromatophores, and the resulting patterns mimic reflections of down-welled light in the water column, suggesting that this behavior may provide a dynamic type of camouflage. Rapid and global pauses in flickering, often before a flashing episode, indicate that flickering is under inhibitory neural control. Although flashing and flickering have not been described in other squid, functional similarities are evident with other species.
H.R. analyzed all video data and prepared the manuscript. W.G. carried out the Crittercam deployments in the field, analyzed PAT tag data and chromatophore time-course data and assisted with manuscript preparation. K.A. carried out Crittercam deployments in the field and provided manuscript edits. L.B. carried out a preliminary analysis of video and sensor data from Crittercam in an undergraduate honors thesis and provided edits to the manuscript. G.M. provided technical and scientific oversight for the Crittercam deployments and provided edits to the manuscript.
The authors declare no competing or financial interests.
This work was supported the US Office of Naval Research (grant number N000140911054 to the University of Texas), the US National Science Foundation (grant numbers OCE 0850839 and IOS 1420693); the National Geographic Society (grant number 8458-08); the Gordon and Betty Moore Foundation through the Census of Marine Life project, Tagging of Pacific Pelagics (TOPP); and National Geographic Television (Dangerous Encounters with Brady Barr).
Supplementary material available online at http://jeb.biologists.org/lookup/suppl/doi:10.1242/jeb.114157/-/DC1
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