Manta Rays: Courtship and Mating
How do the Manta Rays find each other?
In the ocean, manta rays have no dating apps to find a potential mate, so how do they do it? Well, female manta rays become sexually mature around 10 -15 years old, although they only reproduce around every 2-3 years. It is thought that females release a chemical called pheromones, which signals to male manta rays that she is ready to mate. From here, a kind of speed dating occurs as with manta rays, it is the female’s choice as to who she will mate with. The first male manta will hover above the top of the female and test her receptiveness, attracting the attention of other randy male mantas wanting to try their luck. Now for the speed dating element, a chain of male mantas will begin to form a line behind the female, also known as a “courtship train”, each vying for the chance to mate. This train has been recorded to be up to 30 individual male mantas lined up head to tail behind the female. Now the female puts them to the test, swimming in elaborate patterns including somersaults, fast-paced swimming and have even been recorded to jump above the water. These chains can alter in length, and if there is more than one active female in the area, males may switch from line to line.
Picture credit to Guy Steven
Not all trains result in a mating event, as sometimes the female may decide none of the male mantas is up for the task. However, if the female decides there is an appropriate male on the train, she slows down, usually heads to the surface, and waits for the male to make his move. The male uses his front fins, also known as cephalic fins, to guide himself to the left-hand side wing, known as the pectoral fin. From here, he bites down on this fin and uses it to position himself, so the mantas are now belly to belly instead of swimming directly above, enabling him to complete his procreation act. During this act, the female becomes motionless, sending the couple into slow motion spiral through the water column, similar to how a leaf falls from a tree, for around 40 seconds. Once complete, the mantas swim their way in separate directions. On Occasion, however, the females have been witnessed to complete this process with another male a little while later.
One way we, The Manta Trust, monitor manta breeding events is by observing mating scars left behind by the male on the female’s pectoral fin. Those are caused by the male biting the fin of the female manta and are usually white, black or red and circular or oblong, depending on how recently the mating event occurred. Red scars indicate a recent mating event, allowing us to track pregnancies and reproductive trends. Additionally, these scars enable us to identify when a young female moves from a juvenile to a sexually active adult. Over 95% of mating scars are found on the left side, a trend known as lateralisation, found in many species, even humans, in the way that there are more right-handed than left-handed people.