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So what does jellyfish mating look like? How does a Copula sivickisi put the moves on a potential mate?
Ames observed the ritual in the wild before she knew what she was watching. “The first time I saw a male and a female entwined on the surface…I scooped [them] up, and before my very eyes, I saw the male pass this big bundle of red stuff to the female, release her, and she ingested this bundle of red stuff,” Ames recalls. “Within two days, she produced this embryo strand, and when I reared them in the lab, they grew up to be polyps, which are baby jellyfish.”
Like all jellyfish, Copula sivickisi only have one orifice – one tube, called a manubrium (Fig 4) – that serves as mouth, anus, and reproductive channel – so their mating behavior can be difficult to distinguish from other activities, such as eating. But after Ames stumbled upon that first tryst, she decided to study the phenomenon more thoroughly.
In the lab, she found that the Copula sivickisi mating ritual begins when a male takes hold of a female’s tentacle and begins to pull her around in the water (Fig 5). He then draws her close so that their manubria are touching, produces a bundle of red sperm known as a spermatophore (Fig 6) that he deposits onto one of her tentacles (Fig 7), and releases her (Fig 8). Then, just as Ames observed, the female ingests the spermatophore, which fertilizes the eggs she carries inside her bell. A few days later, she produces a sticky strand comprised of tens of thousands embryos (Fig 9).
Ames watched each grouping with a flashlight and observed that females could receive up to eight spermatophores in a two-hour trial period. Each male could produce and transfer as many as six sperm bundles per trial, and they would sometimes initiate the ritual with a female who was still attached to another male. She also found that a male’s size didn’t matter. On average, the small males transferred the same number of spermatophores to females as their larger counterparts.
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