Giant oceanic manta ray
Giant oceanic manta ray Temporal range:
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Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Subclass: | Elasmobranchii |
Superorder: | Batoidea |
Order: | Myliobatiformes |
Family: | Mobulidae |
Genus: | Mobula |
Species: | M. birostris
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Binomial name | |
Mobula birostris (Walbaum, 1792)
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Range of the giant oceanic manta ray | |
Synonyms[citation needed] | |
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The giant oceanic manta ray, giant manta ray, or oceanic manta ray (Mobula birostris) is a species of ray in the family Mobulidae and the largest type of ray in the world. It is circumglobal and is typically found in tropical and subtropical waters but can also be found in temperate waters.[4] Until 2017, the species was classified in the genus Manta, along with the smaller reef manta ray (Mobula alfredi). DNA testing revealed that both species are more closely related to rays of the genus Mobula than previously thought. As a result, the giant manta was renamed Mobula birostris to reflect the new classification.[5]
Description
The giant oceanic manta ray can grow up to a maximum of 9 m (30 ft) in length
The skin is smooth with a scattering of conical and ridge-shaped
Physical distinctions between oceanic manta ray and reef manta ray
The oceanic manta ray is larger than the reef manta ray, 4 to 5 metres in average against 3 to 3.5 metres.[12] However, if the observed rays are young, their size can easily bring confusion. Only the colour pattern remains an effective way to distinguish them. The reef manta ray has a dark dorsal side with usually two lighter areas on top of the head, looking like a nuanced gradient of its dark dominating back coloration and whitish to greyish, the longitudinal separation between these two lighter areas forms a kind of "Y". While for the oceanic manta ray, the dorsal surface is deep dark and the two white areas are well marked without gradient effect. The line of separation between these two white areas forms a "T".
The two species can also be differentiated by their ventral coloration. The reef manta ray has a white belly often with spots between the
Distribution and habitat
The giant oceanic manta ray has a widespread distribution in tropical and temperate waters worldwide. In the Northern Hemisphere, it has been recorded as far north as southern California and New Jersey in the United States, Aomori Prefecture in Japan, the Sinai Peninsula in Egypt, and the Azores in the northern Atlantic. In the Southern Hemisphere, it occurs as far south as Peru, Uruguay, South Africa, and New Zealand.[2]
It is an ocean-going species and spends most of its life far from land, travelling with the currents and migrating to areas where upwellings of nutrient-rich water increase the availability of zooplankton.[13] The oceanic manta ray is often found in association with offshore oceanic islands.[10]
Captivity
There are few public aquariums with giant manta ray in captivity. Since 2009, captive manta rays have been classified as Ꮇ. alfredi and there have been no facilities to display Ꮇ. birostris for some time. [citation needed]
Since late 2018 it has been exhibited at
There are also reports that they were kept at the Marine Life Park, part of the Resorts World Sentosa in Singapore.[16][17]Biology
When traveling in deep water, the giant oceanic manta ray swims steadily in a straight line, while further inshore it usually basks or swims idly. Mantas may travel alone or in groups of up to 50. They sometimes associate with other fish species, as well as
The giant oceanic manta ray sometimes visits a
Males become sexually mature when their disc width is about 4 m (13 ft), while females need to be about 5 m (16 ft) wide to breed. When a female is becoming receptive, one or several males may swim along behind her in a "train". During
The fertilized
Brain size and intelligence
The oceanic manta has one of the largest brains, weighing up to 200 g (five to ten times larger than a whale shark brain), and the largest brain-to-mass ratio of any fish. It heats the blood going to its brain and is one of the few animals (land or sea) that might pass the mirror test, seemingly exhibiting self-awareness.[26]
Status and threats
Natural predation
Because of its large size and velocity in case of danger (24 km/h escape speed),
Fishery
The oceanic manta ray is considered to be
Since the 1970s,[31] fishing for manta rays has been significantly boosted by the price of their gill rakers on the traditional Chinese medicine market.[32] In Chinese culture, they are the main ingredient in a tonic that is marketed to increase immune system function and blood circulation, though there is no strong evidence that the tonic is actually beneficial to health. For this reason and others, gill rakers are sold at relatively high prices – up to $400 per kilogram – and are sold under the trade name pengyusai.[33][31] In June 2018 the New Zealand Department of Conservation classified the giant oceanic manta ray as "Data Deficient" with the qualifier "Threatened Overseas" under the New Zealand Threat Classification System.[34]
Pollution
There is also the threat of microplastics in the diets of oceanic manta rays. A 2019 study in Indonesia's Coral Triangle was performed to determine if the filter-feeding megafauna of the area were accidentally ingesting microplastics, which can be eaten by filter-feeders either directly (by ingesting layers of plastic polymers that float on the surface of the water in feeding areas) or indirectly (by eating plankton that previously ate microplastics). The results of the study provided ample evidence that filter feeders, such as oceanic manta rays, that lived in the area were regularly consuming microplastics. Though it was also proven via stool samples that some of the plastic simply passed through the digestive systems of manta rays, the discovery is a concern because microplastics create sinks for persistent organic pollutants like dichloro-diphenyl-trichloroethanes (DDTs) and polycyclic aromatic hydrocarbons (PAHs). Manta rays that consume microplastics harboring these pollutants can suffer from a variety of health effects that range from short-term negative effects such as the reduction of bacteria in their guts, or long-term effects including pollutant-induced weakening of the population's reproductive fitness over future generations, which could negatively affect population levels of the rays in the future.[35]
M. birostris are also victims of bioaccumulation in certain regions. There has been at least one study that has shown how heavy metals such as arsenic, cadmium, and mercury can be introduced to the marine environment via pollution and can travel up the trophic chain. For example, there was a study in Ghana that involved the testing of tissue samples from six M. birostris carcasses; all of them showed evidence of high concentrations of arsenic and mercury (about 0.155–2.321 μg/g and 0.001–0.006 μg/g respectively). While the sample size was not the most ideal, it is a first step towards further understanding the true amount of bioaccumulation that M. birostris undergoes due to human pollution. These high levels of metals can cause harm to the people who consume M. birostris, and could also cause health problems for the M. birostris species itself. More studies need to be done in order to further confirm the negative health effects of bioaccumulation on M. birostris.[36]
Climate change combined with rising temperatures, are projected to cause a 10% decrease in the global population of phytoplankton with a potential 50% decrease in tropical areas. With these reductions could come a decrease in M. birostris populations.[37]
See also
- Threatened rays
References
- ^ Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Chondrichthyes entry)". Bulletins of American Paleontology. 364: 560. Archived from the original on 2012-05-10. Retrieved 2008-01-09.
- ^ a b Marshall, A.; Barreto, R.; Carlson, J.; Fernando, D.; Fordham, S.; Francis, M.P.; Derrick, D.; Herman, K.; Jabado, R.W.; Liu, K.M.; Rigby, C.L. & Romanov, E. (2022). "Mobula birostris". IUCN Red List of Threatened Species. 2022: e.T198921A214397182. Retrieved 2023-05-05.
- ^ "Appendices | CITES". cites.org. Retrieved 2022-01-14.
- ^ "Mantas at a Glance". The Manta Trust. 2011. Archived from the original on 2013-01-03. Retrieved 2012-04-04.
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- ^ "Giant Manta Ray caught in Batticaloa - Sri Lanka Latest News". Sri Lanka News - Newsfirst. 11 August 2018. Retrieved 9 February 2019.
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- ^ "Mantas at a Glance". Manta Trust. Archived from the original on 2013-01-03. Retrieved 2016-12-15.
- ^ a b Stevens, Guy (2011) "Field guide to the identification of Mobulid rays (Mobulidae)" Archived 2016-10-20 at the Wayback Machine. Manta Trust.
- ^ a b c Passarelli, Nancy; Piercy, Andrew. "Biological profiles: Manta birostris". Ichthyology. Florida Museum of Natural History. Retrieved 2013-09-14.
- ^ "Mantas at a Glance | Manta Trust". www.mantatrust.org. Archived from the original on 2013-01-03. Retrieved 2016-07-19.
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- ^ "LA GRANDE RAIE-MANTA". Nausicaä Centre National de la Mer. Retrieved 2021-12-29.
- ^ "オニイトマキエイ". 美ら海生き物図鑑. Retrieved 2021-12-29.
- ^ Long, Wong Lee. "Singapore Academy of Corporate Management - Singapore Marine Life Park". Retrieved 2018-01-09.
- ^ "Top 5 Things to Do on Sentosa Island". www.marinabaysands.com. Retrieved 2018-01-09.
- ^ ISBN 0-520-22265-2.
- ^ Fisheries, NOAA (2021-10-21). "Giant Manta Ray | NOAA Fisheries". NOAA. Retrieved 2021-11-11.
- ^ "Giant rays shown to be predators of the deep". phys.org. Retrieved 9 February 2019.
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- ^ McDermott, Amy (25 July 2017). "Manta ray brainpower blows other fish out of the water". Oceana. Retrieved 9 February 2019.
- ^ "Natural Predation". Manta Trust. Archived from the original on 2015-07-11. Retrieved 2016-12-15.
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- ^ a b "Manta Fisheries". Manta Trust. Archived from the original on 2013-01-27. Retrieved 2016-12-15.
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- ^ a b "Turning the tide for devil rays". IUCN. 2017-03-30. Retrieved 2021-12-03.
- ^ "Gill Plate Trade". Manta Trust. Archived from the original on 2016-10-25. Retrieved 2016-12-15.
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- ^ "Mantas in a Climate Crisis". Manta Trust. Retrieved 2021-12-03.
External links
- Media related to Manta birostris at Wikimedia Commons
- Photos of Giant oceanic manta ray on Sealife Collection