Clownfish Queue To Have Sex
All Percula Clownfish, Amphiprion percula, are born males! They are Protandrous hermaphrodites that develop into males first, then possibly to females. They form matriarchal social groups within a single Anemone, composing of a dominant breeding pair accompanied by up to 4 non-breeding subordinates. Within this, the largest member would become the one and only breeding female, ranking highest in the hierarchy, followed by the breeding male. Down the ranks the male subordinate decrease in size correspondingly. Should the female of a group die, the dominant male changes sex to become the breeding female, and the next largest non-breeder becomes the breeding male (Fricke 1979; Ochi 1989; Hattori 1994).
To avoid contention in hierarchy, dominants evict possible subordinates that are of similar size to them, mostly occurring at the point of entry into the group. Hence, recruits, or newly-joined, non-breeding subordinates, that start of at the bottom of the ranks, modify their growth rate in consideration of their immediate superior, so as to not elicit eviction. These non-breeders, with non-functioning gonads, have no immediate implication on the fitness of dominant breeders; the significant future benefit being, to replace either of the dominant breeders.
Interestingly enough, the peace-loving subordinate Clownfish do not contest dominants to ascend the ranks. Also, they do not take the option of dispersing from the existing group to potentially take up the mantle of a vacant dominant breeding position at another anemone.
So why don’t these subordinate Clownfish pursue the other strategies for them to breed?
They have seemingly figured out the games of Odds, that queuing to become either of the dominant breeding pair confers to a greater probability than dispersing or winning the contest with the existing larger dominants. Perhaps they had realized that they were poor swimmers and will likely be preyed on beyond the protection of their Anemone’s tentacles.
1) Journal Article
Buston, P. M. (2004). Territory inheritance in clownfish. Royal Society Publishing, 271.
Retrieved April 1, 2013, from
2) Journal Article
Paterson, S. (2003). Size and Growth Modification in Clownfish. Nature, 424. Retrieved
March 29, 2013, from