With an average depth of 3,682 metres, the ocean covers around 70% of Earth’s surface. While life exists throughout most of this vast space, current estimates state that over 90% of species in the ocean remain undiscovered. A recent observation hailing from Raja Ampat in Southwest Papua highlights just how much there is still to learn about our mysterious ocean.

In the productive, nutrient-rich waters of Misool, an island group in southern Raja Ampat in the Ceram Sea famous for its colourful and abundant coral reefs, oceanic manta rays and reef manta rays often thrive alongside one another. New, exciting video documentation has now revealed that they might even do more than that… A team of researchers studying individuals aggregating at a seamount’s cleaning station recently filmed the first-ever known record of courtship behaviour between male oceanic manta rays (Mobula birostris) and a female reef manta ray (Mobula alfredi).

While the first living hybrid of oceanic and reef manta rays had already been identified in the Red Sea off Sudan by analysing its DNA after a pioneering research trip in late 2012, the knowledge about manta rays’ reproductive behaviour is still relatively scarce and stems primarily from reef manta rays as the species tends to show up in shallower waters, making observations easier.

Conservationist and underwater photographer Shawn Heinrichs who has been coming to the region for over 18 years, captured the special moment on his camera as he was documenting the current state of the local reef and the changes in biodiversity throughout the surrounding Marine Protected Areas. He explained: “The ocean turned dark and cloudy when a storm rolled in, and I suddenly spotted manta rays swimming around me frantically. They usually move very gracefully so I thought that this behaviour was worth documenting. I dove down and noticed that an oceanic manta ray was pursuing a reef manta. It struck me suddenly that there was a courtship ritual on its way right in front of me. I had never seen that explicit level of interaction between the two species!”

What Heinrichs learned later is that he had documented the first-ever account of courtship between these two species. “It’s really exciting as there aren’t many places in the world where you can see these two species interact,” added Heinrichs. According to him, Misool’s highly productive environment and location increases the probability of the two species interacting which, in turn, increases the probability of courtship, mating, and hybridization. “While I’ve witnessed pre-courtship rituals here before, I had never actually witnessed the courtship ritual itself with a camera running,” said Heinrichs. “I’ve spent countless hours on this seamount, and I’ve only managed to see this once. As far as I know, I have the only footage of this in the world. The behaviour is not something that can be easily studied, so this really is our only reference point.”

Manta ray courtship rituals are rare to witness, with only a handful of events ever recorded on camera. Even rarer is witnessing the actual mating act. While the birth of a manta ray has – to this date – never been recorded in the wild, one female reef manta ray gave researchers the only documented accounts in an aquarium in Okinawa, Japan. The special moment revealed that the species, like other mobulid rays, give birth to live young which look like small versions of their parents and are entirely independent from the moment they are born.

Under natural conditions, female manta rays become sexually mature at around eight to 10 years old. After internal fertilisation, which means that two rays must physically interact to mate, they give birth on average once every two to five years to one pup – depending on food availability and other habitat variables – after a pregnancy that lasts around 12 to 13 months.

During the courtship act itself, the male ray bites onto the female’s left pectoral fin during the mating process and rolls around to insert his claspers. Copulation lasts approximately 30 seconds during which the negatively buoyant rays sink and may even crash into coral reefs, resulting in visible scratches and scrapes. Another visual sign that identifies a female that has reproduced are mating scars from the male’s firm hold on the female’s wing tips, according to the Manta Trust, a UK manta ray research and conservation charity.

Watch the  video below: