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Entries in behaviour (4)


Sometimes *they* look at us too

Check out this cool bit of footage from our recent research visits to Mexico to study whale sharks with the Georgia Aquarium team.  We were diving under a large aggregation of whale sharks when one of them broke from the surface to come and visit, checking out first one diver, and then the other, possibly attracted by the bubbles.  Whale sharks normally cruise around at the surface, largely indifferent to human presence except for occasionally rolling their eye across you as they pass, but this one was clearly interacting with us.  Colleague Betty Galvan tells me about a small (if 4m could be considered small) female that followed her for 20 minutes in Honduras one time, so interactive she described it as being like a puppy.  I suspect, when conditions are right, whale sharks can be curious or even inquisitive critters.  Its hard to prove, but I don’t think there’s much doubt from the video.  The aquarium has been conducting a behavioural study on the collection animals for some time, but more work on their behaviour in the natural setting is desperately needed.  Hopefully the aquarium study can refine the techniques needed to get out there and understand what they do in the field.


You can follow my YouTube channel here, or the aquarium’s channel here. Footage Copyright 2010 Bruce Carlson/Georgia Aquarium and used with permission


Look who's talkin'

Interesting news in a study thats in pre-publication in Ethology about mixed species schools of dolphins and the communication patterns that take place within them.  The author, Laura May-Collado of the University of Puerto Rico, hypothesised that when bottlenosed dolphins and Guyana dolphins school together, differences between their respective songs ought to be exaggerated in order to avoid confusion and enhance communication within species.  [Whales have been shown to alter their song to meet surrounding conditions, most recently in papers that describe long-term increases in song volume to offset the increasing background of human-made noise in the oceans.]  What she found was the exact opposite: calls became more homogeneous (with less variation between species), with the signal stucture (the waveform of the whistle as seen, for example, on an oscilloscope) converging on a form intermediate between the bottlenosed and Guyana whistles. Her first conclusion is that this represents a change on the part of the smaller Guyana dolphin to reduce social stress (placation, if you will) but its also possible that the dolphins might be using a common language.  If so, that would be one of the first examples of interspecies communication and it would be quite different from how humans do it, wherein one participant nearly always tries to change to the other participants language, not that boh participants find an intermediate language (I guess this is because human languages are too complex to easily invent intermediate forms).  Dr. May-Collado was unable to determine which explanation was the correct one because her equipment couldn’t distinguish which individuals were making the sounds, but its certainly a tantalizing view into the chatter that goes on between species in the ocean.

Guyana dolphin in front, bottlenosed behind. Click pic for original story



Your calamari wants a flat screen

ResearchBlogging.orgOctopuses and their relatives are just incredible animals.  Not only do they manage to coordinate hundreds of suckers on 8 arms simultaneously without tripping over themselves (I can't even remember what I ate for breakfast) and have the most advanced eyes in the invertebrate world, but they can do other cool stuff like eat sharks,  fit through holes much smaller than themselves, use tools and learn from each other.  Now a new study has shown that they can tell the difference between regular TV and HD.  How did they determine this?  Simply, as it turns out.  The octopus show no reaction to footage of other octopus or crabs shown to them on regular TV screens.  When shown real crabs or crab footage in hi-def, however, the octopus lunged as if to attack the hapless decapod (video link).  In other words, octopus can tell the difference between real and imagery, if the image is not of high enough quality.
The explanation appears to lie not in the resolution of the screen (how small the pixels are) so much as how fast the picture can be draw and redrawn on the screen.  The picture on a TV screen is constantly being created line-by-line from the top of the screen in a process called rastering.  We don't perceive this rastering because it happens faster than we can see; faster than our "critical flicker frequency".  Well, not everyone has the same critical flicker frequency, and nor do all televisions have the same rastering rate.  Most hi-def TV's have a higher frequency (120 or even 240Hz, or times-per-second).  It may be that low-def TV is below the octopus critical flicker, but hi-def is above it.  In this way, they would see a sort of strobing effect in normal footage, but the hi-def stuff would look like, well, a crab.
The authors also noticed that the octopus showed "episodic personality", which is to say they were interested in the crab (or footage of another octopus) some times but not others.  I'm not sure I would class that as evidence of personality, just a less-than-100%-predictable response to a stimulus.  Having said that, ocotpus do have obvious personalities, which is one reason people are so drawn to them.  That, and sweet chilli sauce...

Pronk, R., Wilson, D., & Harcourt, R. (2010). Video playback demonstrates episodic personality in the gloomy octopus Journal of Experimental Biology, 213 (7), 1035-1041 DOI: 10.1242/jeb.040675


Octopus using tools

I couldn't let this go by.  My wife is something of a behavioural expert and a very good animal trainer, and we have often discussed how intelligent octopus are.  In that respect this isn't news, but the tool use is pretty cool and very exciting for behavioural scientists, what with them being invertebrates and all (the octopus that is, not the scientists...).