Spontaneous Ejaculation in a Wild Indo-Pacific Bottlenose Dolphin (<i>Tursiops aduncus</i>)

<div><p>Spontaneous ejaculation, which is defined as the release of seminal fluids without apparent sexual stimulation, has been documented in boreoeutherian mammals. Here we report spontaneous ejaculation in a wild Indo-Pacific bottlenose dolphin (<i>Tursiops aduncus</i>), and present a video of this rare behavior. This is the first report of spontaneous ejaculation by an aquatic mammal, and the first video of this behavior in animals to be published in a scientific journal.</p></div

Spontaneous ejaculation by a wild Indo-Pacific bottlenose dolphin off Mikura Island, Japan.

<p>(A) Dense seminal fluid was ejaculated from the tip of the penis with initial contraction of the peduncle muscle downward. (B) A few seconds after the first ejaculation of seminal fluid, the remaining seminal fluid was ejaculated for 0.86 s (26 frames at (1/30 s)/frame).</p