Humboldt squid (Dosidicus gigas) close up at 250 meters. Credit: NOAA/CBNMS.

Deep living squid get their glow on

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Peer-reviewed: This work was reviewed and scrutinised by relevant independent experts.

Observational study: A study in which the subject is observed to see if there is a relationship between two or more things (eg: the consumption of diet drinks and obesity). Observational studies cannot prove that one thing causes another, only that they are linked.

Animals: This is a study based on research on whole animals.

Bioluminescence is a key form of communication for deep-ocean-dwelling creatures. In a new study, US researchers used high-definition video cameras to observe 30 Humboldt squid  in the Pacific Ocean’s California Current at depths of up to 848m. The squid put on flashing and flickering colour displays when foraging as a group, which may help reduce competition between individuals hunting the same prey. According to the authors, their findings suggest a new level of complexity in how residents of the deep ocean communicate visually.

Journal/conference: PNAS

Link to research (DOI): 10.1073/pnas.1920875117

Organisation/s: Stanford University, USA

Funder: National Science Foundation, The David and Lucile Packard Foundation, Department of Biology of Stanford University

Media Release

From: PNAS

A study finds evidence suggesting complex visual signaling in deep-ocean-dwelling cephalopods. Cephalopods that inhabit the tenebrous depths of the ocean use pigmented cells called chromatophores embedded in skin to communicate through visual signaling. However, the level of sophistication in such visual signals is unclear. Benjamin Burford and Bruce Robison used high-definition video cameras mounted on remotely operated vehicles to examine visual signaling in 30 Humboldt squids (Dosidicus gigas) at depths between 266 and 848 m in the Pacific Ocean’s California Current, the squids’ natural daytime haunt. At these depths, the squids put on flashing and flickering color displays when foraging with other squids of the same species. Together with other patterns, pale and dark illumination along the longitudinal axis of the squids’ bodies suggested signaling of intent during competitive foraging. Despite the density and frenzy of foraging shoals, the squids appeared to avoid jostling for prey, suggesting a perceived response to visual signaling of foraging intent. Analysis of pigmentation patterns during pursuit and capture of prey suggested a role for syntax in the squids’ signaling that evoked linguistic elements such as message signifiers, modifiers, and positionals. While the squids’ pigmentation patterns are produced by the overlying layer of chromatophores in skin, hundreds of subcutaneous photophores, which illuminate the muscles of the fins, mantle, arms, and head from within, are strewn across the squids’ bodies. Analysis of captured squids suggested that the social messaging encoded in the squids’ pigmentation patterns unfolds against a glowing backdrop of photophore-enabled bioluminescence, which potentially enhances pattern visibility under low light. According to the authors, the findings raise the possibility of a previously undescribed level of semantic complexity in visual communication among denizens of the deep ocean.

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