Stomatopod Log Entry: Color Preference in a Mantis Shrimp (June 7,1998)
Contributor: Alan San Juan
Mantis shrimps sometimes close off their dwellings using rocks, shells, and other handy and nearby objects. Since there is considerable evidence that stomatopods are able to see in color, I was interested in determining whether they had a preference for the type and color of objects that they use to seal the openings to their homes.
I placed a small (3 cm long) mantis shrimp in a 1.5 g tank whose bottom was covered only with extremely fine (1 mm or so), light-brown pebbles. The mantis shrimp made its home in an empty snail shell, and I then placed pebbles of varying colors within the tank. The pebbles were of similar sizes (3/4 to 1 cm) but of different colors (red, blue, green), and I mixed the lot so as to prevent the buildup of piles of similarly-colored pebbles. I placed equal numbers of red, blue, and green pebbles for each experiment (usually 18-20 of each), and I then counted the number of pebbles daily to see whether the mantis shrimp made use of any of the colored pebbles in its walls.
The results showed that this particular individual showed a strong preference for blue and red pebbles. Although I have yet to do a statistical analysis of the results, this preference is most likely statistically significant.
There are of course serious defects in the "experiments" that I did, most noticeably in the facts that I had no control samples (eg., controlling for difference in the chemical "feel" of the different colored pebbles, which may have accounted for the selection, as opposed to color differences), and I only tested a single individual, as opposed to many and different mantis shrimps.
Nevertheless, the results are somewhat interesting, and seem to confirm previous studies which showed that mantis shrimps have color vision. More interesting is this individual's seeming preference for pebbles of a certain color. One possibility is that the "darker" hues of the red and blue pebbles may have been more to the liking of the normally retiring mantis shrimp, as opposed to the more brightly-colored green pebbles, which could attract attention to its dwelling.
Web Site Author: A. San Juan
Site Created February 3, 1998