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Department of Invertebrate Zoology

Sapphirina auronitens
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A side view of a juvenile Carybdea sivickisi jellyfish swimming in the dark of night

Fig 4. A side view of a juvenile Copula sivickisi jellyfish swimming in the dark of night. Note the central gelatinous tube that spirals at the bottom where the four mouth lips meet (only three lips visible in photo). This tube is called the manubrium, and it serves as the mouth, anus and reproductive channel. Image courtesy: Cheryl (Lewis) Ames.

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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.”

"...and before my very eyes..." Listen to Cheryl Ames' "first time" observations. (67 seconds)

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.

Fig. 5
The start of the reproductive courtship ritual between a male and a female Carybdea sivickisi jellyfish
Fig. 6
A male Carybdea sivickisi with its tentacles intertwined with those of the female produces a spermatophore
Fig. 7
A male and female Carybdea sivickisi jellyfish are entwined as the male passes the pale orange sperm strands to the female which is formed into a spermatophore on the female's tentacle
Fig. 8
Following the transfer of the spermatophore from the male jellyfish to the female jellyfish, the female Carybdea sivickisi jellyfish uses her tentacles to insert the sperm bundle into the manubrium inside her bell

Figures 5 through 8. The Copula sivickisi mating ritual. (Click each image for more details). Images courtesy: Alvaro Migotto.

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).

Watch a video of the Copula sivickisi mating ritual

A female Carybdea sivickisi jellyfish releases an embryo strand about 60 hours after sexual reproduction

Fig 9. A female Copula sivickisi  jellyfish releases an embryo strand about 60 hours after sexual reproduction. The beige-colored strand consists of thousands of embryos linked together by a mucous covering. Note also the dark spots around the margin of the female's bell. These velar spots are only present in mature females, and may play a factor in mate choice in males. Image courtesy: Cheryl (Lewis) Ames.

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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