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For the past 14 years, scientists have been watching manta rays pick each other up at a known hotspot in the Maldives, recording 229 courtship events. They recently compiled their observations into a report that is, according to Guy Stevens, founder of Manta Trust and lead author, “the most detailed window into the sex lives of mantas.”
While the two species of manta rays documented in the study, giant oceanic manta rays and reef manta rays, mate in different places and usually at different times of the year, their mating rituals are quite similar.
The courtship often begins when a female releases pheromones that draw the attention of males in the vicinity. But when a male moves in, the female zooms off. Other males may also join the chase, and with the males in hot pursuit, the female twists and turns in the water, deking around obstacles and navigating at high speed in an effort to judge her suitors’ physical prowess. To attract more males to choose from, she may breach the surface in acrobatic leaps.
“It appears that it’s all building the excitement, trying to engage as many males in the event as possible, which gives her maximum choice later on in the process,” Stevens says.
The chase can last for hours as males drop out. If the female is satisfied with the sole remaining suitor, she slows down, swims toward the surface, and mates with him. Despite the extended foreplay, intercourse only lasts about 30 seconds as the rays slowly sink toward the seabed.
Sometimes the females will repeat the dance in the following days. The female can collect and store the sperm from several males for years. She’ll wait until ocean conditions are right before releasing the sperm to fertilize her eggs.
Stevens says the ritual is likely so elaborate because mantas only tend to give birth every four or five years. The graceful fish may live as long as 40 to 50 years, but females aren’t sexually mature until they’re 15. While males aren’t choosy, females want to ensure the best genes are passed along to their offspring.