Though little is known of the reproductive cycle of manta rays and we have yet to observe oceanic mantas give birth in the wild, scientists have now observed manta at different stages of their sex lives. Here is a brief overview of the fascinating mating dances, pregnancies and baby manta births.
Sexual maturity
Manta rays get sexually mature at around 8 to 15 years old and have been observed to reproduce at up to 50 (years old they can live up to 75 years). When a female manta is ready and wants to mate she will release pheromones (sex hormones) into the water and interested males will get the signal that they can now woo her. Fertility is very low in comparison with other fish because females usually have 1 or 2 babies maximum at a time. This only happens once every 2-5 years. Manta s have a 30-40 year fertility range but half of births occur during the first 24 or 25 years after sexual maturity.
Mating train (or Mantas' conga line?): the sexy courtship dance
The start of the mating ritual is fittingly called ‘manta train’ (or it could have been named ' Manta Conga' slightly less fittingly). One female manta ray swims up front, followed by several male mantas. The largest manta train witnessed included 20 male mantas, both young and old, chasing the female.The mating train dance can go on for several weeks and usually eventually most males lose interest. However, this does not mean that the last male dancer wins. Scientists have observed bored males returning to the mating train later on and winning the reproductive game. Pregnant females have been also observed leading a manta conga too, maybe just for the love of the dance.
There is no definitive research to suggest manta rays follow a specific method when deciding on a partner, but what seems clear is that the females lead and decide.
What does Manta ray sex look like?
When he is ready to get it on, the male manta ray swims above the female and holds her left wingtip to stop her from moving (he bites his partner’s left pectoral fin). He then moves around to position his body facing his partner( yes, missionary position). He inserts one of his claspers ( two small fins that are basically manta willies- yes, they have 2) into her cloaca (punani) to achieve egg fertilization. The claspers are extensions of the pelvic fins and are how male mantas 'deliver' sperm (in)to the female. The male has two claspers, but only one is used at a time (in case you were wondering).
Before the transmission of sperm, a gland is activated at the base of the claspers, which secretes a thick fluid. Not much is known about this fluid or its purpose, but scientists think that it may have something to do with lubrication of the clasper groove; perhaps to prevent loss of sperm during copulation. For mantas, the boys also get wet, in more ways than one.
Baby mantas!
Most animals fit into two categories: they give birth to live young which have grown in their stomach (viviparous, like mammals) or they lay eggs and the young hatch when ready (oviparous, like birds or reptiles). Certain species of sharks and rays (a.k.a elasmobranchs), including Manta rays, have developed a combination of these two methods: they are ovoviviparous, the offspring grows in an egg inside the mother’s body and hatches inside, being born alive.
Inside the egg, embryos are fed by the yolk. Gestation is approximately 1 year (12 to 13 months). The young mantas are independent from the first moment they leave the mother’s body. Since they have few natural predators, they don’t need parental care as such.
Baby manta rays can measure more than 1 meter in diameter (wing tip to wing tip) and are exact replicas of an adult. During the first year of life, babies tend to double in size.
So next time you see a train of Mantas, in Nusa Penida, Bali, for instance, you will know what is going on!
Opmerkingen