Manta ray
Manta rays are large rays belonging to the genus Mobula. Three species are known: M. birostris, the largest at in width, M. yarae, which reaches, and M. alfredi, the smallest at. All three have triangular pectoral fins, horn-shaped cephalic fins and large, forward-facing mouths. They are classified among the Myliobatiformes and are placed in the family Myliobatidae. They have one of the highest brain-to-body ratio of all fish, and can pass the mirror test.
Mantas are found in warm temperate, subtropical and tropical waters. All three species are pelagic; M. birostris and M. yarae migrate across open oceans, singly or in groups, while M. alfredi tends to be resident and coastal. They are filter feeders and eat large quantities of zooplankton, which they gather with their open mouths as they swim. However, research suggests that the majority of their diet comes from mesopelagic sources. Gestation lasts over a year and mantas give birth to live pups. Mantas may visit cleaning stations for the removal of parasites. Like whales, they breach for unknown reasons.
M. birostris and M. alfredi are both listed as vulnerable by the International Union for Conservation of Nature. Anthropogenic threats include pollution, entanglement in fishing nets, and direct harvesting of their gill rakers for use in Chinese medicine. Manta rays are particularly valued for their gill plates, which are traded internationally. Their slow reproductive rate exacerbates these threats. They are protected in international waters by the Convention on Migratory Species of Wild Animals, but are more vulnerable closer to shore. Areas where mantas congregate are popular with tourists. Only a few public aquariums are large enough to house them.
Etymology
The name "manta" is Portuguese and Spanish for mantle, a type of blanket-shaped trap traditionally used to catch rays. Mantas are known as "devilfish" because of their horn-shaped cephalic fins, which are imagined to give them an "evil" appearance.Taxonomy
Manta rays are members of the order Myliobatiformes which consists of stingrays and their relatives. The genus Manta is part of the eagle ray family Myliobatidae, where it is grouped in the subfamily Mobulinae along with the smaller Mobula devil rays. In 2018, an analysis of DNA, and to a lesser degree, morphology, found that Mobula was paraphyletic with respect to the manta rays; that is, some members of genus Mobula are closer related to the members of the genus Manta than they are to fellow Mobula, and the researchers recommended treating Manta as a junior synonym of Mobula.Mantas evolved from bottom-dwelling stingrays, eventually developing more wing-like pectoral fins. M. birostris still has a vestigial remnant of a sting barb in the form of a caudal spine. The mouths of most rays lie on the underside of the head, while in mantas, they are right at the front. The edges of the jaws line up while in devil rays, the lower jaw shifts back when the mouth closes. Manta rays and devil rays are the only ray species that have evolved into filter feeders. Manta rays have dorsal slit-like spiracles, traits which they share with the devil fish and Chilean devil ray.
Species
The scientific naming of mantas has had a convoluted history, during which several names were used for both the genus and species. All were eventually treated as synonyms 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 ascribed to Johann Julius Walbaum by some authorities and to Johann August Donndorff by others. The specific name alfredi was first used by Australian zoologist Gerard Krefft, who named the manta after Prince Alfred.A 2009 study analyzed the differences in morphology, including color, meristic variation, spine, dermal denticles, and teeth of different populations. Two distinct species emerged: the smaller M. alfredi found in the Indo-Pacific and tropical East Atlantic, and the larger M. birostris found throughout tropical, subtropical and warm temperate oceans. The former is more coastal, while the latter is more ocean-going and migratory. A 2010 study on mantas around Japan confirmed the morphological and genetic differences between M. birostris and M. alfredi.
A third possible species, preliminarily called Manta sp. cf. birostris, reaches at least in width, and inhabits the tropical West Atlantic, including the Caribbean. In 2025, it was formally described as the Atlantic manta ray.
Fossil record
While some small teeth have been found, few fossilized skeletons of manta rays have been discovered. Their cartilaginous skeletons do not preserve well, as they lack the calcification of the bony fish. Only three sedimentary beds bearing manta ray fossils are known, one from the Oligocene in South Carolina and two from the Miocene and Pliocene in North Carolina. M. hynei is a fossil species dating to Early Pliocene North America. Remains of an extinct species have been found in the Chandler Bridge Formation of South Carolina. These were originally described as Manta fragilis, but were later reclassified as Paramobula fragilis.Characteristics
Manta rays have broad heads, triangular pectoral fins, and horn-shaped cephalic fins located on both sides of their mouths. They have horizontally flattened bodies with eyes on the sides of their heads behind the cephalic fins, and gill slits on their ventral surfaces. Their tails lack skeletal support and are shorter than their disc-like bodies. The dorsal fins are small and at the base of the tail. Mantas can reach. In both species, the width is about 2.2 times the length of the body; M. birostris reaches at least in width, while M. alfredi reaches about. Their skin is covered in mucus. Mantas normally have a "chevron" coloration. They are typically black or dark on top with pale markings on their "shoulders". Underneath, they are usually white or pale with distinctive dark markings by which individual mantas can be recognized, as well as some shading. Individuals can also vary from mostly black to mostly white. These color morphs appear to be products of neutral mutations and have no effects on fitness. A pink manta ray has been observed in Australia's Great Barrier Reef and scientists believe this could be due to a genetic mutation causing erythrism. The fish, spotted near Lady Elliot Island, is the world's only known pink manta ray.Image:Manta alfredi cruising - journal.pone.0046170.g002A.jpg|thumb|right|alt=Ventral view| M. alfredi with mouth closed, cephalic fins rolled and ventral surface showing distinctive markings
The two species of manta differ in color patterns, dermal denticles, and dentition. M. birostris has more angular shoulder markings, ventral dark spots on the abdominal region, charcoal-coloured ventral outlines on the pectoral fins, and a dark colored mouth. The shoulder markings of M. alfredi are more rounded, while its ventral spots are located near the posterior end and between the gill slits, and the mouth is white or pale colored. The denticles have multiple cusps and overlap in M. birostris, while those of M. alfredi are evenly spaced and lack cusps. Both species have small, square-shaped teeth on the lower jaw, but M. birostris also has enlarged teeth on the upper jaw. Unlike M. alfredi, M. birostris has a caudal spine near its dorsal fin.
Mantas move through the water by the wing-like movements of their pectoral fins. Their large mouths are rectangular, and face forward. The spiracles typical of rays are vestigial and concealed by small flaps of skin, and mantas must keep swimming with their mouths open to keep oxygenated water passing over their gills. The cephalic fins are usually spiraled but flatten during foraging. The fish's gill arches have pallets of pinkish-brown gill rakers, which are made of spongy tissue that collects food particles. Mantas track down prey using visual and olfactory senses. They have one of the highest brain-to-body mass ratios and the largest brain size of all fish. Their brains have retia mirabilia which may serve to keep them warm. M. alfredi has been shown to dive to depths over, while the Chilean devil ray, which has a similar structure, dives to nearly.
Behavior and ecology
Swimming behavior in mantas differs across habitats: when travelling over deep water, they swim at a constant rate in a straight line, while further inshore, they usually bask or swim idly around. Mantas may travel alone or in groups up to 50. They may associate with other fish species, as well as sea birds and marine mammals. Mantas sometimes breach or leap out of the water. Individuals in a group may make aerial jumps in succession. Mantas may leap forward and re-enter head first, tail first or make somersaults. The reason for breaching is not known; possible explanations include communication, or the removal of parasites and remoras.Mantas visit cleaning stations on coral reefs for the removal of external parasites. The ray adopts a near-stationary position close to the coral surface for several minutes while the cleaner fish feed. Such visits most frequently occur when the tide is high. Individual mantas may exhibit philopatry by revisiting the same cleaning station or feeding area repeatedly and appear to have cognitive maps of their environment. In addition, it has been confirmed that reef manta rays form a bond with a specific individual and act together.
Mantas may be preyed upon by large sharks, orcas and false killer whales. They may also harbor parasitic copepods. Mantas can remove internal parasites by sticking their intestines up to out of their cloaca and squeezing them out, often while defecating. Remoras adhere themselves onto mantas for transportation and use their mouths as shelter. Though they may clean them of parasites, remoras can also damage the manta's gills and skin, and increase its swimming load.
In 2016, scientists published a study in which manta rays were shown to exhibit behavior associated with self-awareness. In a modified mirror test, the individuals engaged in contingency checking and unusual self-directed behavior.