When do jellyfish mate

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In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript. Some box jellyfish display elaborate mating behaviours and even use their toxic stinging cells to ensure successful fertilization. Many jellyfish reproduce using external fertilization, but in a few box jellyfish, fertilization can occur internally.

In one species Copula sivickisi ; pictured , the male transfers a sperm package into the female's stomach to fertilize the eggs after the animals entangle their tentacles.

The females then lay strands of embryos. Anders Garm and his team at the University of Copenhagen studied the sex organs of the jellyfish under a microscope and located the stinging cells in the sperm package and in the female gonad. The sperm package becomes attached to the female gonad and sperm cells are partly digested, releasing their nuclei, which are then taken up by the female sex organ.

The stinging cells probably help the sperm package to attach, and protect the embryos once they are laid. Soon after, they go on to mate with other adults. Fully developed jellyfish embryos will hatch to become free-swimming larvae called planulae.

From there, a couple of different things can happen. In some species, the planulae develop into adult madusae. Sometimes, the sessile polyps will grow into individual medusae. Other times, the polyps reproduce again, this time asexually, by budding, or producing a clonal outgrowth on its side. Sometimes, the bud will become a polyp clone that also attaches itself to the substrate. Other times, the outgrowth will develop into a baby jellyfish called an ephyra, which grows up to become a medusa.