Steger, R., & Caldwell, R. L. 1983. Intraspecific deception by bluffing: A defense strategy of newly molted stomatopods (Arthropoda: Crustacea). Science, 221, 558-560.

Mantis shrimp of the genus Gonodactylus defend cavities by using their enlarged second maxillipeds as clubs to smash prey and conspecifics alike. However, like all crustaceans, they must molt. At this time, they are unable to do any damage to hard-shelled intruders. This then begs the question, how do these animals defend their homes in such a state?

The authors define a bluff in this genus as a misrepresentation of fighting ability. Gonodactylus uses various displays to warn conspecifics of their fighting abilities. The two most common are strike-attacks, and meral spread displays (leaning out of den and spreading their raptorial appendages). A newly molted animal is said to be bluffing when it displays, as it has no fighting ability whatsoever. This soft-shelled period immediately after molting lasts from four to ten days.

The authors placed control individuals (either newly molted or intermolt) in a 30 cm arena with a cavity in which they took up residence. They then placed into the arena a specimen that was intermolt (hard-shelled). Intermolt residents tended to attack the intruder (using the meral spread display in only 4 out of 19 trials). Newly molted individuals used the meral spread display in 15 out of 17 trials.

In conclusion, newly molted members of this genus defend their homes by bluffing their potential usurpers. It is interesting to note that if the bluff was called, the newly molted resident always chose to flee. This proves further that these animals are attempting to bluff the intruders.

(250 words)

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(posted Dec. 22 2010)