Manta rays are the big rays belonging to the genus Manta . The larger species, M. birostris , reaches a width of 7 m (23Ã, ft 0Ã, in) while the smaller,
Mantas are found in warm, subtropical and tropical climates. Both species are pelagic; M. birostris migrates across open oceans, singly or in groups, while M. alfredi tends to be populated and coastal. They are filter feeders and eat large amounts of zooplankton, which they swallow with their mouths open when they swim. Pregnancy lasts more than a year and mantas give birth to a live puppy. Mantas can visit the cleaning station to remove parasites. Like a whale, they break, for unknown reasons.
Both species are listed as vulnerable by the International Union for Nature Conservation. Anthropogenic threats include pollution, entanglement in fish nets, and direct harvest for gill filters for use in Chinese medicine. Their slow reproductive rate exacerbates this threat. They are protected in international waters by the Convention on Migrants Wild Species, but are more vulnerable closer to shore. The area where mantas gather is popular with tourists. Only a few public aquariums are large enough to accommodate them.
Video Manta ray
Taxonomy and etymology
The name "manta" is Portuguese and Spanish for mantle (cloak or blanket), a kind of blanket-shaped trap traditionally used for capturing rays. Mantas are known as "demons" because of their horn-shaped cephalic fin, which is conceivable to give them an "evil" appearance.
Manta rays are members of the Mylijectformes order which consists of stingrays and their families. The genus of Manta is part of the Myliobatidae eagle ray family, where it is grouped in the Mobulinae subfamily along with the demonic Mob. By 2017, DNA analysis - and, to a lesser extent, morphology - found that Mobula was paraphyletic with respect to manta rays, and they recommended to treat Manta. as a junior synonym Mobula .
Mantas evolved from stingrays that lived below, eventually developing more pectoral fins like wings. M. birostris still has the remaining residue from the sting of a thorn in the form of a caudal spine. Most of the mouth's rays are located at the bottom of the head, while in manta they are right in front. Manta rays and demonic rays are the only kind of ray that has evolved into a filter feeder.
Species
The scientific naming of mantas has a tortuous history, in which several names are used for both genera ( Ceratoptera , Brachioptilon Daemomanta and Diabolicthys ) and species (such as vampyrus , americana , johnii and pregnant ). All end up being treated as a synonym of the single species Manta birostris . The genus name Manta was first published in 1829 by Dr. Edward Nathaniel Bancroft of Jamaica. The specific name birostris is considered to be derived from Johann Julius Walbaum (1792) by several authorities and to Johann August Donndorff (1798) by another. The name alfredi was first used by the Australian zoologist Gerard Krefft, who named manta after Prince Alfred.
The authorities are still unanimous and some argue that black morphs are a species distinct from most white morphs. This proposal was discounted by a 2001 mitochondrial DNA study of both. A 2009 study analyzed morphological differences, including color, meristic variations, spine, skin denticles (dental scales) and teeth from different populations. Two different species emerged: the smaller M. alfredi found in the Indo-Pacific and Northeast Atlantic, and the greater M. birostris found throughout the tropical, subtropical and warm tropical oceans. The first is more coastal while the latter more ocean and migrate. A 2010 study on mantas in Japan confirmed the morphological and genetic differences between M. birostris and M. alfredi.
The third possible species, originally called Manta sp. cf. birostris , reaching at least 6 m (20 ft) wide, and inhabiting the tropical western Atlantic, including the Caribbean. This and M. birostris occur in sympatry.
Fossil record
While several small teeth have been found, several skeletons of manta ray fossils have been found. Their cartilage skeletons do not survive well because they do not have bony fish calcifications. Only three layers of sediment carry the known manta ray fossils, one from Oligocene in South Carolina and two from the Miocene and Pliocene in North Carolina. The remains of extinct species have been found in the Chandler Bridge Formation in South Carolina. It was originally described as Manta fragilis but was later reclassified as Paramobula fragilis .
Maps Manta ray
Biology
Appearance and anatomy
Manta rays have wide heads, triangular pectoral fins, and horn-shaped cephalic fins located on either side of their mouths. They have horizontally leveled bodies with eyes on the sides of their heads behind cephalic fins, and gill slits on their ventral surfaces. Their tail has no bone support and is shorter than their disc-shaped bodies. The small dorsal fin and the base of the tail. The largest manta can reach 1,350 kg (2,980 lb). In both species, the width is approximately 2.2 times the body length; M. birostris reaches at least 7 m (23Ã, ft) of width while M. alfredi reaches about 5.5 m (18 ft). On the back, mantas are usually black or dark with a pale sign on their "shoulders". In general, they are usually white or pale with distinctive dark markings in which each mantas can be identified. Black color morphs are known to exist. The skin is covered in mucus that protects it from infection.
Both manta species differ in color patterns, skin denticles, and teeth. M. birostris has more angled shoulder marks, larger ventral dark spots on the abdominal area, charcoal-colored belly lines on pectoral fins and dark mouths. The shoulder markings of M. alfredi are more rounded, while the ventral points are located near the posterior end and between the gill slits, and the mouth is white or pale. Denticles have multiple valves and overlap in M. birostris , while the M. alfredi is evenly distributed and does not have cusp. Both species have small tooth-shaped teeth in the lower jaw but M. birostris also has teeth enlarged in the upper jaw. Unlike M. alfredi, M. birostris has a caudal spine near the dorsal fin.
Mantas moves through the water by the pectoral wing motions of their chest, which push the water backward. Their large mouth is rectangular, and is forward-faced compared to other types of rays and skates with the mouth facing down. The typical spiracles of the rays are vestigial, and the manta must swim continuously to keep the oxygen water through its gills. The cephalic fin usually rotates, but flattens during feeding. The gill arch of the fish has a pink spongy tissue pallet that collects food particles. Mantas tracks the prey using the visual and olfactory senses. They have one of the highest brain-to-body mass ratio and the largest brain size of all fish. Their brains have a mirabilia retia that keeps them warm. M. alfredi has been proven to dive to a depth of more than 400 m, while their relative Mobula tarapacana, which has a similar structure, dives to nearly 2000 m; retia mirabilia may serve to prevent their brains from becoming cold during such dives into the cooler subsurface waters.
Life cycle
Mating occurs at different times throughout the year in different parts of the manta range. Dating is difficult to observe in these fast-swimming fishes, although marriage of "trains" with some individuals swimming close to each other is sometimes seen in shallow waters. The marriage sequence may be triggered by a full moon and appears to be initiated by men following behind a woman as she walks about 10 km (6.2 miles) per hour. She makes a recurring effort to hold the pectoral fin with her mouth, which may take twenty or thirty minutes. As soon as he has a tight grip, he turns and presses his stomach side against his. He then inserts one of the claspers into the cloaca where they remain for sixty to ninety seconds. Claspers form tubes that deliver sperm from genital papillae; siphon pushes semen into the fallopian tubes. Men continue to hold women's pectoral fins with teeth for a few minutes further as they continue to swim, often followed by up to twenty other men. The couple then split up. For some reason men almost always catch left pectoral fins, and women often have scars depicting this.
The fertilized egg develops inside the female ovum. First they are put into the egg box while the developing embryo absorbs the egg yolks. After hatching, the puppies stay in the fallopian tubes and receive additional nutrients from the secretion of milk. Without umbilical cord or placenta, the unborn baby relies on buccal pumping to obtain oxygen. The size of the parent is usually one or sometimes two. The pregnancy period is estimated to be twelve to thirteen months. When fully developed, the pupus resembles an adult miniature and is removed from the fallopian tube without further parental care. In wild populations, the two-year interval between births may be normal, but some individuals become pregnant for several consecutive years, indicating an annual ovulation cycle. The Okinawan Churaumi aquarium has some success in breeding M. alfredi , with one woman giving birth in three consecutive years. In one of these pregnancies, the pregnancy period is 372 days and at birth the child is 192 cm (76 inches) wide and weighs 70 kg (150 pounds). In southern Africa the adult male MOS is adult at 4 m (13 ft) while the woman reaches maturity a little more than that. In Indonesia, the male M. birostris appears adult at 3.75 m (12 feet) while the adult female is about 4 m (13 ft). In southern Africa, M. alfredi matures at a width of 3 m (10 ft) for men and 3.9 m (13 ft) for women. In the Maldives, adult males are width 2.5 m (8 ft 2 in) while females mature at 3 m (9.8 ft). In Hawaii, the adult M. alfredi is 2.8 m (9 ft 2 in) wide for men and 3.4 m (11 ft) for women. Mantas women look mature at 8-10 years. Manta rays can live for 50 years. Behavior and ecology
Behavior swimming in mantas differs in habitat: when traveling on deep water, they swim at a constant rate in a straight line, while further beaches they usually sunbathe or swim around. Mantra can travel alone or in groups of up to 50. They can associate with other fish species as well as seabirds and marine mammals. Mantas sometimes breaks, jumps partially or entirely out of the water. Individuals in groups can make air jumps one by one. These jumps come in three forms: a forward leap where the fish land first, a jump similar to the first tail back or somersault. The reason for the violation is unknown; possible explanations include ritual marriage, birth, communication, or parasite removal and commensal remobs (suckerfish).
As a filter feeder, manta rays consume large amounts of zooplankton in the form of shrimp, krill and planktonic crabs. Manta individuals eat about 13% of their body weight each week. When looking for food, slowly swim around the prey, lead it into a tight "ball" and then accelerate the organism that is gathered with the mouth wide open. If the ball is very solid, manta might get through it. When feeding, they even flatten their cephalic fins to channel food into their mouths and small particles are collected by the tissue between gill arches. A total of fifty individual fish can gather in one plankton-rich eating place. Manta itself is preyed on by large sharks and by killer whales. They can also be bitten by cookiecutter sharks, and harbor paradite copepods.
Mantas visited a clearing station on the reef to remove external parasites. This ray adopts a near-stationary position close to the surface of the reef for several minutes while the cleaning fish consume the attached organism. This kind of visit is most common when the tide is high. In Hawaii, sewers provide cleaning; some species feed around the mouth manta and gill slits while others show the rest of the body surface. In Mozambique, the master fish sergeant cleans the mouth while the crab fish concentrates on the bite wound. M. alfredi visited the cleaning station more often than M. birostris . Individual Mantas can re-visit the same cleaning stations or eating places repeatedly and appear to have their cognitive map of the environment.
Distribution and habitat
Mantas is found in tropical and subtropical waters in all the world's great oceans and also explores into temperate oceans. The furthest from the recorded equator is North Carolina in the United States (31ºN) to the north, and North Island of New Zealand (36ºS) to the south. They prefer water temperatures above 68Ã,  ° F (20Ã,  ° C) and M. alfredi mostly found in the tropics. Both species are pelagic. M. birostris lives mostly in the open sea, traveling with the current and migrating to areas where upwelling nutrient-rich water increases the concentration of prey.
Fish already fitted with radio transmitters have traveled as far as 1,000 km (620 miles) from where they were captured and descended to a depth of at least 1,000 m (3,300 ft). M. alfredi is a more populous and coastal species. Seasonal migration does occur, but they are shorter than M. birostris . Mantas are common around the coast from spring to autumn, but travel further offshore during the winter. They stay close to the surface and in shallow water during the day, while at night they swim in deeper depths.
Conservation issues
Threat
The biggest threat to manta rays is overfishing. M. birostris is not evenly distributed in the oceans, but is concentrated in areas that provide the necessary food resources, while M. alfredi is even more localized. Their distribution is fragmented, with little evidence of interpopulation mixing. Due to their long life spans and low reproductive rates, overfishing can greatly reduce the local population with little chance that people from elsewhere will replace them.
Commercial and artisanal fisheries have targeted mantas for meat and their products. They are usually caught with nets, trawlers and spears. Manta has been caught by fisheries in California and Australia for their oils and skins; the latter being used as abrasive. Their meat can be eaten and consumed in some countries, but not as attractive as other fish. The demand for their gill gills, the cartilage structure that protects the gills, has recently entered Chinese medicine. To meet the growing demand in Asia for gill miners, targeted fisheries have been developed in the Philippines, Indonesia, Mozambique, Madagascar, India, Pakistan, Sri Lanka, Brazil and Tanzania. Every year thousands of manta rays, especially M. birostris, are captured and killed solely by their gill ribs. A fishery study in Sri Lanka and India estimates that more than 1000 are sold in the country's fish market every year. By comparison, the M. birostris population in most of the key aggregation sites around the world is estimated to have fewer than 1000 individuals significantly. Fishery targets for manta rays in the Gulf of California, western coast of Mexico, India, Sri Lanka, Indonesia and the Philippines have dramatically reduced populations in these areas.
Manta rays are subject to other anthropogenic threats. Because mantas must swim constantly to flush oxygen-rich water above their gills, they are susceptible to further winding and aggravation. Mantas can not swim backwards and, because of their prominent cephalic fins, are prone to entanglement in fishing lines, ghost webs, and even loose mooring lines. When caught, mantas often try to free themselves by overtaking, ensnare themselves further. Loose, trailing lines can wrap and cut the path to the flesh, resulting in permanent injury. Similarly, mantas entangled in a gill net designed for smaller fish. Some mantas are injured by collision with boats, especially in areas where they are gathered and easily observed. Threats or other factors that may affect manta numbers are climate change, tourism, pollution from oil spills, and microplastic consumption.
Status
In 2011, it became very protected in international waters because it was included in the Convention on Wild Animals Migrants. CMS is an international treaty organization that deals with the conservation of species and migratory habitats on a global scale. Although each country has protected manta rays, fish often migrate through unregulated waters, placing them at an increased risk of overfishing. IUCN declared M. birostris to 'Vulnerable to extinction risk' in November 2011.
In the same year, M. alfredi was also classified as 'Vulnerable' to a local population of less than 1000 individuals and little or no exchange between sub-populations. The Manta Trust is a UK-based charity dedicated to research and conservation efforts for manta rays. The organization's website is also a source of information for manta and biology conservation.
In addition to this international initiative, some countries take action on their own. New Zealand has banned manta sighting since the introduction of the Wildlife Law in 1953. In June 1995, the Maldives banned the export of all species of light and parts of their bodies, effectively halting manta fishing because there had never previously been a fishery for local consumption. The government strengthened this in 2009 with the introduction of two marine protected areas. In the Philippines, taking mantas was banned in 1998, but this was canceled in 1999 under pressure from local fishermen. Fish stocks were surveyed in 2002, and the ban was re-enacted. Miscarriages or murders in Mexican waters were banned in 2007. This prohibition may not be strictly enforced, but the law is more applied rigidly on Isla Holbox, an island off the Yucat Peninsula, where manta rays are used to attract tourists.
In 2009, Hawaii became the first of the United States to introduce a ban on murder or manta rays. Previously, there was no fisheries for mantas in the state, but migratory fish passing through the islands is now protected. In 2010, Ecuador introduced a law banning all fishing for mantas and other rays, their retention as bycatch, and their sales.
Relationships with humans
The ancient Moche Peruvians worshiped the sea and its animals. Their art often depicts manta rays. Historically, it has been feared because of their size and strength. Sailors believe that they eat fish and can sink a boat by pulling anchors. This attitude changed around 1978 when divers around California Bay found them calm and that they could interact with animals. Some divers photographed themselves with mantas, including Jaws author Peter Benchley.
Aquarium
Due to its size, it is rare for mantas to be kept in captivity and some of the aquariums currently display it. One of the notable individuals is "Nandi", a manta ray that was accidentally caught in a shark net in Durban, South Africa, in 2007. Rehabilitated and breeding aquarium at uShaka Marine World, Nandi moved to the larger Georgia Aquarium in August 2008, where it lives in the 23,848-m 3 (6,300,000-US gal) "Ocean Voyager" exhibit. The second manta ray joined the aquarium collection in September 2009, and the third was added in 2010.
The Atlantis resort on Paradise Island, Bahamas, hosted the manta named "Zeus" which was used as a research subject for three years until it was released in 2008. The Okinawan Churaumi Aquarium is also a manta ray house in the "Kuroshio Sea" tank, the largest aquarium tank in the world. The birth of the first manta ray in captivity occurred there in 2007. Although this child did not survive, the aquarium has seen the birth of three more manta rays in 2008, 2009, and 2010.
Tourism
Sites where manta rays gather to attract tourists, and see mantas generate substantial annual income for local communities. Tourist sites are in the Bahamas, Cayman Islands, Spain, Fiji Islands, Thailand, Indonesia, Hawaii, Western Australia and the Maldives. Mantas is very popular because of its huge size and because they are easily habituated with humans. Scuba divers may get a chance to watch mantas who visit the clearance stations and night dives allowing viewers to see mantas who eat in plankton attracted by the lights.
Ray benefits local tourism and visitors by raising awareness of natural resource management and educating them about animals. It can also provide funding for research and conservation. Regular irregular interactions with tourists can negatively impact fish by disrupting ecological relationships and increasing disease transmission. In Bora Bora, excessive swimmers, sailors, and jet players are causing local manta ray residents to leave the area.
By 2014, Indonesia has brought a ban on fishing and exports because it has realized that stingray tourism is more economically advantageous than letting fish get killed. Manta dies worth $ 40 to $ 500 while manta ray tourism can bring in $ 1 million during the life of a manta ray. Indonesia has 5.8 million square kilometers (2.2 million sq mi) of oceans and is now the largest refuge in the world for manta rays.
See also
- Endangered ray
- Manta Matcher - Wildbook for Manta Rays
References
External links
- Microdocs: Manta ray
- Manta Ray videos and news from BBC including new species likely recordings
- Manta birostris , IUCN Red List of Endangered Species
- Manta ray media in ARKive
- Diving with Mantas in the Azores
- Meet Mantola Maldives Manta Trust .
- Manta Matcher - Wildbook for Manta Rays
Source of the article : Wikipedia
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