Do axolotls change sex?

Natalie Kim Bjorklund umbjork1 at cc.UManitoba.CA
Fri Jan 24 08:42:45 EST 1997

A situation came up in our lab, again, which has me wondering about this 
one. We recieved a shipmate of eight healthy female axolotls in the 
summer. We were assured they were all female and we checked them 
ourselves just to be certain. Today I came in to feed the animals and 
discovered, to my complete astonishment, that there were two spawnings in 
the tank. One is near hatching and the other is late gastrula stage.

We placed these eight new animals in isolation, four per tank upon 
arrival although they appeared in perfect health. About two weeks after 
they arrived we had a cyclopic parasite resembling the pictures of Ergasilus
infesting several other tanks. Because of this, we ended up extending the 
period of isolation much longer than we normally would have. We only just 
got rid of the Ergasilus (I hope) and since it's not the time of year we 
want spawnings in our lab, we simply left all the animals in the tanks 
they were happy in. Also, we are between students, some had left and 
others while due to start had not yet begun to work in the lab so there 
was only myself and one other person. I know I did not move animals 
around and the other person also swears he did not change any animals.

Even more puzzling, the animal which is now an apparently fully 
functional male, does not have the typical thin male build but, except 
for the cloaca, is built like a female. I contacted the group we acquired 
the animal from and was told it is about 3 years old, 2 at minimum. It is 
also a rather large animal, as big as any of the females we have.

I have two possible explanations. One is that one of the female animals 
got out of the tank, crawled to the other side of the room, jumped into 
the tanks of our original females and disappeared into the crowd. Shortly 
after that, a large male jumped out of his tank, crawled across the 
floor, and jumped into the tank with the three females. This male 
also managed to cleverly disguise himself so that he would appear like 
an entirely different animal from any other males we have noticed before, 
"in drag" as it were, so that I assumed since the great switcheroo that he 
was a she.

The second explanation is that she really was a she but then became a he.

I have had this seem to happen before but I have never been so sure that 
the animals have not been mixed.

Are there any known cases of axolotls changing sex?

Natalie K Bjorklund
University of Manitoba

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