Crayfish enjoy a bit of sub-dom: official

Scientists probe 'humping' behaviour

Scientists from Georgia State University have rather splendidly discovered that crayfish "act out elaborate rituals of dominance and submission", Reuters reports.

Specifically, Fadi Issa and Donald Edwards found said crustaceans "display... a complex ritual, when two males engaged in pseudocopulatory behaviour to signify their dominance relationship" which was followed by "a reduction in aggression and an increased likelihood of the subordinate's survival".

Indeed, this is not just a bit canine rolling on your back when the top dog's around - it's a matter of life or death for crayfish. The researchers noted that "lower-ranking crayfish that did not go along with another male's overtures were killed, dismembered, and partially eaten".

Issa and Edwards, who monitored sub-dom behaviour among a group of 20 males, said it was "most common when two strange males first met, and appeared to defuse tensions after a few days". They further explained: "These effects are similar to those of copulation between male and female crayfish, and such copulation can also begin with an aggressive encounter and has been seen as an extension of male dominance behaviour. Moreover, if the female refuses the male's attempts to mate, she can be killed."

The scientists concluded by saying "the findings in invertebrates showed such behaviour was common in the animal world and may have evolved more than once over time". This suggests a bit of sub-dom is "useful for survival", they added.

Issa and Edwards' findings are available in the journal Current Biology. We look forward to their forthcoming paper on Promiscuous lesbianism among spider crabs as a mechanism for social harmony. ®

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