Fascinating new squid behaviour in nature
The squid is one creature that really needs technology to observe its incredible moods
of colour and rapid movement. This is now firmly in place with a video camera that can be parcelled with the animal as it travels. Hannah Rosen and her 4 colleagues from Stanford University and the National Geographic Society have studied the Humboldt squid in situ in this paper in the Journal of Experimental Biology, Chromogenic behaviors of the Humboldt squid (Dosidicus gigas) studied in situ with an animal-borne video package.
The point of research in the case of this jumbo flying squid is to learn how it behaves naturally. The predator can be found in the Gulf of California and is now Hollywood material up to depths of 70m. Try asking that of most dynamic display artists. The animal does indeed produce fantastic mating and signalling displays. These consist of flashing patterns at other individuals or flickering, when other squid are not communicating. The flickering has the effect of mimicking down-welled light patterns at whatever depth the squid is at. Camouflage from other predators is obviously a likely use for this effect.
This Dosidicus species is large enough to carry the National Geographic Crittercam. The currents of the Pacific Coast of the Americas are this animal’s natural pathways. The Califorrnia Current, the Humboldt Current itself and the Costa Rica Dome are obvious habitats for a pelagic squid, while the Equatorial Upwelling Zone can be included as part of its distribution. Other squid, lantern fish and pteropods are quite small prey but bigger squid get very ambitious with bigger fish. On the other hand, sperm whale, sharks and some of those big fish also eat the quid. Then there are the fisheries that predate this human food item, which forms the 12th largest fishery of a single species!
During the day, the animals swim down several hundred metres, while their nocturnal activity tends to be restricted to 10-50m depths. Acoustic sampling has revealed aggregations and even cooperative groups of squid, but it has been impossible to work out behaviour before this research. With 3 deployments of the Crittercam, the individuals always dived at speeds of up to 1m s-1 This escape bid was compounded by other squid ripping off Crittercam 1. These guys really are cooperative!
This was further shown by the large numbers of squid the other 2 cameras encountered as their carrier moved around. Arm to arm contact involving mating behaviour happened 5 times, but only lasted a few seconds. Arm splaying was also displayed, as a sort of greeting from 2 others to the camera squid, on one occasion. Colour displays were noted 8 times.
Under artificial lights, these displays have been reported before. The edges of the fins, the keels of each arm and the top of the head all change colour. The small sample here displayed high amplitude with well-defined peaks when flashing took place between 2 or more individuals. The entire body oscillated between pale and dark colours at a frequency of 2-4Hz. (another species has now been observed doing this - Stenoteuthis oualaniensis, the purpleback squid.) The videos are freely available as supplementary material here We have a story of the mimicry in a deep-sea squid here.
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