They are gentle giants of the sea, gliding silently on wings that can span 7m, but little is known about manta rays except that they face a high risk of extinction in the wild.
To learn more about their migratory patterns and how to protect them, researchers are tagging 30 with microchips that will track their movements for up to a year.
The project by United States-based environmental group Conservation International and Resorts World Sentosa's (RWS) SEA Aquarium is the first under a five-year partnership inked in January. The tie-up will focus on conservation, public education and supporting regional projects.
The 30 mantas will be tagged in Indonesian waters, namely in Bali, Raja Ampat, Berau and Komodo, where they gather in large numbers.
These locations comprise four manta tourism sites in Indonesia, where people "pay top dollar" to swim or snorkel with them, said Conservation International's senior adviser, Dr Mark Erdmann.
The manta-ray tagging project is believed to be one of South-east Asia's largest. Each tag costs about US$6,000 (S$7,500) and can track data such as depth and temperature of the water and real-time location of the mantas using Global Positioning System technology. Manta rays are not known to be found in Singapore's waters, although they may occasionally swim past.
National University of Singapore marine biologist Chou Loke Ming said it would be useful to find out more: "In order to protect a species, we need to know more of their behaviour and movement so that we can find effective ways of conserving it."
RWS added that the data could be used by the Indonesian Ministry of Marine Affairs and Fisheries to develop conservation and tourism management policies.
Information collected from the project will also be displayed at the aquarium, one of the few in the world to keep the animals in captivity. This month, visitors can also find out more about them at a manta-ray exhibition there. Aside from viewing the three reef manta rays in the aquarium's Open Ocean Habitat section, they can take part in activities such as talks and manta feeding shows.
Although the creatures are seldom kept in aquariums due to their large size, Dr Erdmann said it "was not a welfare issue" as the rays under RWS' care are healthy. "We believe that a public aquarium plays a tremendous role in increasing awareness of ocean issues," he said.
Five facts about manta rays
There are two species of manta ray: the reef manta ray and the oceanic manta ray.
The oceanic manta ray is the larger of the two, with a width span of up to 7m. The reef manta ray's width span is about 5.5m. Both are listed as "vulnerable" on the International Union for Conservation of Nature (IUCN) Red List, which means they are considered to be facing a high risk of extinction in the wild.
Manta rays reproduce very slowly - they reach sexual maturity only between eight and 12 years of age and deliver only one pup every three to four years.
Manta rays are being hunted for their gill rakers, which are used in Chinese medicine. Practitioners believe consuming the cartilage supporting the gills will boost the immune system and help reduce toxins and fever.
Manta rays have a skeleton made up of cartilage, just like the shark. This is why both manta rays and sharks are classified under the same class of fish.
Manta rays are sometimes known as the "sea devil" because of their horn-shaped fins. They are filter feeders that feed only on plankton. They do not have any stinging barbs and are harmless to humans.
Professor Chou Loke Ming (NUS marine biologist) and Dr Mark Erdmann (senior adviser of Conservation International), IUCN
This article was first published on Sep 4, 2014.
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