Reef Manta Ray

The reef manta ray, scientifically known as Mobula alfredi, is a distinguished species within the Mobulidae family and ranks as one of the largest rays globally. It is surpassed in size only by the giant oceanic manta ray. The species was first described in 1868 by Gerard Krefft, then director of the 🇦🇺 Australian Museum, who named it in honor of Alfred, Duke of Edinburgh - the first British royal family member to visit 🇦🇺 Australia. Initially classified under the genus Manta, it was re-categorized in 2017, along with other mantas, into the genus Mobula.

Typically, reef manta rays measure between 3 and 3.5 meters in disc width, reaching a maximum of approximately 5.5 meters, and can weigh up to 700 kilograms. Although previously grouped with M. birostris, the reef manta ray was recognized as a distinct species in 2009. This species primarily inhabits the tropical and subtropical Indo-Pacific regions, with occasional reports from the tropical East Atlantic, but none from the West Atlantic or East Pacific. Unlike the giant oceanic manta ray, the reef manta ray is more commonly associated with shallower, coastal habitats, although some local migrations are noted.

While Mobula alfredi and Mobula birostris share similarities in appearance, they can be distinguished by certain characteristics, despite their overlapping distributions. The reef manta ray can reach a disc size of 5 meters, though commonly observed sizes range from 3 to 3.5 meters. These rays are known for their dorsoventrally flattened bodies and prominent triangular pectoral fins. At the front, they possess cephalic fins, which are extensions of the pectoral fins used to channel water into their substantial mouths for feeding.

Additional features include eyes and spiracles located on the side of the head behind the cephalic fins, five gill slits on the ventral surface, a small dorsal fin, and a long, whip-like tail without spines, distinguishing them from related devil rays (Mobula spp.). The dorsal coloration varies from dark black to midnight blue with lighter markings, while the ventral side is typically white, sometimes displaying dark spots and blotches.

Differentiation between Mobula alfredi and Mobula birostris can be achieved through size and color patterns, the latter offering a more reliable identification method. The reef manta ray's dorsal surface includes two lighter areas forming a "Y" shape, while the oceanic manta ray features two distinct white markings separated by a "T" shaped line. The ventral surface also serves as an identification point, with distinctive spot patterns between species.

The reef manta ray inhabits tropical and subtropical Indo-Pacific regions, often frequenting areas like Hawaii (🇺🇸 United States), 🇫🇯 Fiji, 🇵🇫 French Polynesia, and the 🇵🇭 Philippines, with a preference for coastal regions. Although predominantly sedentary, they may undertake short migrations to pursue zooplankton, having established specific feeding and cleaning locations in proximity to coastlines, reefs, and islands. They lead a pelagic lifestyle, filtering sea water for zooplankton, and can live up to 50 years, forming social communities within certain populations.

Remarkably, reef manta rays in 🇳🇨 New Caledonia (🇫🇷 Overseas France) have been recorded diving up to 672 meters in search of food, facilitated by specific adaptations that allow them to exploit colder waters. Their reproductive strategy is ovoviviparous, with eggs developing within the female's oviduct. Offspring rely on maternal secretions for nourishment after hatching, with a typical gestation period thought to last 12-13 months.

Despite their size and speed, which reduce vulnerability to natural predators, reef manta rays occasionally fall prey to predators such as large sharks, false killer whales, and killer whales. The species is currently listed as vulnerable by the IUCN, attributed to significant population declines due to overfishing. The demand for their gill rakers, driven by the unverified medicinal claims in traditional Chinese medicine, exacerbates threats to their sustainability, highlighting the need for protective measures due to their low reproductive rates and delayed sexual maturity.