While working at an island that’s known as “the home of the manta ray,” it’s easy for most of us staff to get jaded at seeing one or two manta rays…per day. Maybe they do a quick cruise past, or maybe a stop at the cleaning station. But when these mantas do aggregate around this small island on the Great Barrier Reef, those are the days that turn into pure magic. And it reminds us all as to why these animals are so spectacular to interact with.
Manta rays, more specifically Manta alfredi, are unique in the contrast between their large size and inquisitive behavior around humans. Despite reaching average lengths of three to five meters wingtip to wingtip, they are filter feeders and seek out the smallest creatures in the ocean to feed on. The diets of manta rays are found to consist mostly of different types of zooplankton, small creatures that range from microscopic single-celled organisms to the larvae of larger animals like crabs, octopuses, and fish. Zooplankton are heterotrophic, meaning that they obtain their energy from feeding on other organisms including phytoplankton and other zooplankton. In this photo series, all of those small dots sparkling in the photos indicate a high number of plankton.
According to scientists studying the island aggregation site, the higher biomass of zooplankton seems to be a result of “local concentration and retention processes around the island”. Though still unknown why these zooplankton blooms around the island happen, when it does become what we call “manta soup,” the foraging behaviour of the manta rays gives guests and staff some unforgettable experiences. The elasmobranchs ensure filter-feeding efficiency by looping around consistently in nutrient-dense areas. All one must do is stay in that same spot and wait for the mantas to swoop in and detour around you – though with strong currents, this is often more easily said than done. However, some days you get lucky when the weather window blesses you with no wind, high zooplankton biomass, and an influx of manta rays.
These photos come from a day like that, making it almost too easy for an amateur photographer like me to capture these charismatic animals. The mantas were swooping in and out, with some of the females displaying quite pregnant bellies. Like any aggregation site, tourism operators greatly benefit from the frequency at which these animals appear. Their docile and curious nature also makes them excellent flagship species for marine conservationists. Listed as Vulnerable to Extinction by the IUCN, these experiences with the public allow for an opportunity to discuss the challenges our oceans are facing, and why protection is of the utmost importance.
