By Misty Lang

Fontenot (1999) cites the ability to identify the sex of A. tridactylum externally; however, we were unable to do so with our specimen. Males are reported to display a light gray or pink color inside their cloaca (Fig. 1), whereas females are brown (‍‍‍‍‍‍‍Fontenot 1999‍‍‍‍‍‍‍). Because the specimen examined for this project was preserved and not fresh, the coloring may have been off due to effects of preservation or the preservative itself.

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Figure 1. Ventral view of the open cloaca of A. tridactylum.

To be certain, the sex of A. tridactylum can be determined upon opening the abdominal cavity and examining the gonads (Fontenot 1999). We identified our specimen to be male, as indicated in Figure 2 below. Females can be identified internally by the presence of oviducts and ovaries.

Although cats also have internal fertilization, their reproductive systems have little in common with A. tridactylum otherwise. Cat fetuses are supplied with nutrition by a placenta while in utero, and young are nurtured by their mother's milk. Male gonads in the cat are external, and female gonads are internal. Cats are viviparous (live birth) and the amphiuma is oviparous (egg laying). Like the amphiuma, sharks have cloacas. Male shark cloacas have an additional feature called a clasper that assists with copulation, and female sharks have shell glands, ovaries, and some species of sharls give birth to live young.

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Figure 3. Comparison of testes. Photo credit: M. Lang & N. Thach.


References

Bishop, S. C. (1943). Handbook of salamanders: The salamanders of the United States, of Canada, and of Lower California. Ithaca, New York: Comstock Pub. Co., 56-57p.

Fontenot, C. (n.d.). Reproductive biology of the aquatic salamander Amphiuma tridactylum in Louisiana. Journal of Herpetology, 100 p. Retrieved April 10, 2015, from http://www.southeastern.edu/acad_research/depts/biol/faculty/pdf/fontenot1999.pdf