Melanistic Mantas

It goes without saying that we started December’s Marine Megafauna week at Nusa Penida’s world famous Manta Point. Situated towards the lower end of the island’s south-west coast, the Manta Point dive site attracts thousands of divers each year due to almost guaranteed daily manta sightings for divers and snorkellers alike.

Melanistic Manta Ray, Nusa Penida. Photo By Steve Woods

We were treated to over a dozen reef mantas (Mobula alfredi) on the first dive and our students were immediately able to start gathering data for MantaMatcher and practising identifying their sex and level of maturity. Our group was also lucky enough to encounter a few of Nusa Penida’s infamous melanistic mantas.

Contrary to popular opinion, melanistic mantas are not a separate species to reef or oceanic mantas (Mobula birostris); they are simply examples of a pigmentation variation known as melanism. Melanism is a phenomenon that occurs in mantas and other organisms and is the result of individuals having a high level of dark pigmentation in their skin than other members of their species. It is considered the opposite of albinism. Melanistic mantas are not present throughout all manta populations but are fairly common in the Nusa Islands’ population.

Whilst the year-round sightings of reef mantas might lead one to believe that their populations are booming, the species is listed as vulnerable on the IUCN Red List. Oceanic mantas are currently listed as endangered. Both species face an increasing number of threats from both targeted fishing and bycatch, and efforts need to be made to ensure that their populations don’t substantially decrease further, otherwise we might not have the pleasure of sharing our oceans with these magnificent creatures in the not-too-distant future.

Other megafauna treats throughout the week included hawksbill and green turtles (Eretmochelys imbricata and Chelonia mydas), spotted eagle rays (Aetobatus narinari), a brownbanded bamboo shark (Chiloscyllium punctatum), and out-of-season bumphead sunfish (Mola alexandrini).

Mola on Nusa Penida, Bali. Photo by Steve Woods

Our next Marine Megafauna weeks begin on January 28th and March 18th – join us to learn about and experience some of Nusa Penida’s extraordinary megafauna first-hand!