September 17 is World Manta Day, a day to celebrate the marvelous mobula rays and how to protect these increasingly endangered rays.
- Manta rays are relatives of all sharks and rays in the Elasmobranchii, all having skeletons made of cartilage rather than bone.
- Every manta ray has a unique spot pattern on its ventral surface that can be used to identify them, as unique as our fingerprints.
- Manta rays are gentle giants, with individuals of Mobula birostris reaching 22 feet from wingtip to wingtip and weighing over two tons.
- Despite their size, manta rays feed on fish eggs, larvae and small animals called zooplankton.
- Mantas give birth to a single pup after a gestation period of over one year.
- Mantas have the largest brain to body ratio, with convulations in the cerebrum like higher mammals.
- Mantas are gentle and curious and support tourism industries for divers and snorkellers.
Manta Rays are Endangered
The International Union for Conservation of Nature and Natural Resources (IUCN) Red List of Threatened Species, lists the giant Manta ray (Mobula birostris)”endangered.” Reef mantas (Manta birostris), Red List status is “vulnerable”. Both species are listed under CITES Appendix II, regulating trade of their gill rakers yet both species populations are in decline.
Learn How Divers are Documenting and Protecting Mantas
Threats to Manta Rays
- Manta Rays are caught in nets and killed a bycatch in fisheries, and in some countries are eaten as food.
- Climate change is impacting the range and abundance of the zooplankton which mantas require for food. Coral reef loss and bleaching is reducing their habitat.
- The greatest threat to mantas and their cousins the devil rays is the demand for their gill plates. These are sought after in China and SE Asia as traditional medicine as a presumed remedy for respiratory ailments. The filaments that the rays use to filter their food from the water are sold for up to $500 per kilogram.
- TCM practitioners sell the rakers, known as peng yu saias, in an ingredient for soup that they claim boosts the immune system by reducing toxins and enhancing blood circulation. Other purported medical benefits include curing cancer, chickenpox, throat and skin ailments, male kidney issues and in other TCM, fertility issues.
- In a 2012 study by WildAid estimated the market for gill rakers was at least 61,000 kilograms a year, with an estimated value of $11.3 million.
- The researchers found that direct tour operator revenue at just seven sites totals $27 million a year, and estimated the global tourism value of rays at more than 100 Million dollars per year.
Download a free Giant Manta Ray Science Sheet
Manta Rays Endangered by Sudden Demand from Chinese Medicine, Scientific American, By John R. Platt January 17, 2012