University of South Florida St. Petersburg Student Research Journal, Vol. 2, Issue 1, article 1 :Geometric Probability of Mating Success for the Bottlenose Dolphin, Tursiops truncatus

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Student Research Journal (USFSP)

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Publication Date


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February 2012

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February 2012




The bottlenose dolphin, Tursiops truncatus, mates in the non-traditional side-by-side position or the front-to-front (ventroventral) position. Because neither the male nor the female can see their genitals during mating, their bodies must be geometrically aligned for males to successfully deliver their sperm into the female's vagina. In this study, a conservative estimate of the random probability of mating success was calculated in the same way as one would calculate the random probability of a dart hitting the center of a target. One would determine the area of the bull's-eye relative to the area of the entire target. To determine the probability of the male's penis randomly hitting the female's vaginal area, we calculated the area of the vagina relative to the female's frontal area and estimated that the probability of random mating success for dolphins was ~ 1.6% or fewer than 2 chances out of a hundred. Several adaptations for increasing mating success have evolved including the male's prehensile (grasping) penis which allows him to penetrate the female from any angle whether they are mating side by side or front to front.


University of South Florida St. Petersburg


Mentored by Dr. Leon Hardy and Dr. Deby Cassill

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