Manta Rays mate belly to belly, and are ovoviviparous. Females give birth to only 1-2 pups at a time, which are already 4ft across when born. Their age of sexual maturity and overall lifespan is unknown.
Manta Rays are basically harmless to humans, but one should be careful around them due to their large size. They are currently listed as Near Threatened by IUCN.