OCTOPUS REPORT
Field Trip Dates: 13-19 December 2004
Roger T. Hanlon
Marine Biological Laboratory
Woods Hole, MA 02543 USA
I had three goals for this trip; two were met, one was not, and an unexpected 4th goal was realized and met. Thus, this was a highly successful field research trip.
Goal 1 was to determine commonly available octopus species in Saba. We found 4 species that were day-active: Octopus vulgaris, O. defilippi, O. burryi, and O. filosus. Increased searching would have revealed another few species, but finding 3 of the 4 in the same small area is considered an advantage for future study.
Goal 2 was to learn something about octopus food habits by collecting prey remains from octopus dens. This was not done for lack of time.
Goal 3 was to study camouflage in octopus. This was highly successful. We studied the same individual Octopus vulgaris for 4 days in a row on Tent Reef at 7m depth. I was able to obtain ca. 60 minutes of video of changeable camouflage. Most importantly, I was able to obtain 145 high-quality digital still images of octopus camouflage as well as background habitat. These images will form the basis for an initial quantitative analysis of camouflage matching.
The digital still photographic images were made possible thanks to the use of a Nikon Coolpix 8700 camera and Ikelite underwater housing. This camera provides 8 megapixel images, and delivers them in the “camera raw” format that is essential for quantitative analysis. I am extremely grateful for the opportunity to use this instrument because it allows me to take my study to another, more complex, level of analysis. The camera and housing worked fine.
Goal 4 was not anticipated before the trip, yet it materialized on Day 2 of the underwater research. Small peacock flounder, Bothus lunatus, were found in the Tent Reef area, and I was able to video tape these flounders as they moved around and camouflaged themselves. This will add a good comparison to the octopus camouflage study.
Next year we can continue more of the octopus and flounder camouflage changes. Furthermore, we should pursue an anecdotal observation that Octopus defilippi can mimic the swimming actions of flounder. If proven, this would be the first time that flounder mimicry by octopus has been described in the Atlantic Ocean.
