Manta rays are large flattened fish in the genus Manta.
Broadly speaking, manta rays live in tropical, subtropical and temperate oceans worldwide.
There are two species of manta ray:
• the giant oceanic manta ray (Manta birostris)
• the reef manta ray (Manta alfredi)
The giant oceanic manta ray can grow to a disc size of up to 7 m (23 ft) with a weight of about 1,350 kg (2,980 lb) but average size commonly observed is 4.5 m (15 ft).
The reef manta ray can grow to a disc size of up to 5 m (16 ft) but average size commonly observed is 3 to 3.5 m (11 ft).
Both species have triangular pectoral fins, horn-shaped cephalic fins, large forward-facing mouths and gills in the lower body, through which it obtains oxygen from water.
The fish’s gill arches have pallets of pinkish-brown spongy tissue that collect food particles.
Manta rays have approximately 300 rows of skin-covered teeth in its lower jaw.
Their skeleton is composed of cartilage and not bone.
Their tails lack skeletal support and are shorter than their disc-like bodies. Their tails also lack venomous tail spikes that all other rays have.
Manta rays have the largest brain of all the world’s fishes, and much remains to be discovered about its intelligence and social interactions.
Dorsally, mantas are typically black or dark in color with pale markings on their “shoulders”.
Ventrally, they are usually white or pale with distinctive dark markings by which individual mantas can be recognized.
Manta rays move through the water by the wing-like movements of their pectoral fins, which drive water backwards.
They can swim up to 24 kilometers (15 miles) per hour.
Manta rays must swim continuously to keep oxygenated water passing over their gills.
Both species are pelagic. The word “pelagic” is derived from Greek πέλαγος (pélagos), meaning ‘open sea’.
The giant oceanic manta ray spend 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. The oceanic manta ray is often in association with offshore oceanic islands.
Compared to the giant oceanic manta ray, the reef manta ray tends to be found in shallower, more coastal habitats, but local migrations are sometimes reported.
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 consume the attached organisms.
Mantas are common around coasts from spring to fall, but travel further offshore during the winter.
They keep close to the surface and in shallow water in daytime, while at night they swim at greater depths.
Fish that have been fitted with radio transmitters have travelled as far as 1,000 km (620 mi) from where they were caught and descended to depths of at least 1,000 m (3,300 ft).
Mantas may travel alone or in groups of up to 50 and sometimes associate with other fish species, as well as sea birds and marine mammals.
Despite their status as an ocean giant, manta rays feed on some of the smallest organisms in the sea! They are planktivores, feeding especially on zooplankton; tiny animals such copepods, mysid shrimps and arrow worms. Mantas are known to make seasonal migrations in order to take advantage of particularly abundant areas of food.
An individual manta eats about 13% of its body weight each week.
Mantas senses of vision and smell are acute, allowing them to locate their prey. Once prey is located, the manta rays herd their food by swimming around a group of plankton in tightening circles until there is a concentrated mass of the organisms. Then the manta ray tightens its cephalic fins around its mouth to form a funnel and swims, open-mouthed, in a straight line through the mass. Spongy plates along the animal’s gills collect the food, and the filtered water passes through the gills back into the ocean. The food is then pushed into the manta ray’s stomach.
As many as fifty individual fish may gather at a single, plankton-rich feeding site.
Mantas sometimes breach, leaping partially or entirely out of the water. These leaps come in three forms: forward leaps where the fish lands head first, similar jumps with a tail first re-entry or somersaults. Like whales, they breach, for unknown reasons; possible explanations include mating rituals, birthing, communication, or the removal of parasites and commensal remoras (suckerfish).
Mating takes place at different times of the year in different parts of the manta’s range.
Manta rays are ovoviviparous. The female gives birth to live offspring, but these develop in eggs inside the mother. After a gestation period of twelve to thirteen months, the female manta rays give birth to a single pup (although occasionally they may also give birth to twins), which measures roughly 1.5 meters (5 feet) across from wing-tip to wing-tip at birth.
Manta rays may live for as long as 50 years.
Because of their large size only the largest of marine predators, such as the great white, tiger, greater hammerhead and bull sharks, or the false killer whale and orca would attempt to attack an adult manta ray.
In some parts of the world, there are manta fisheries. The flesh of the manta is not widely consumed, but there is a market for its liver oil and its abrasive skin. The gill rakers, which protect and cover the gills, are collected and sold as a Chinese medicinal product.
Both species are classified as “vulnerable” in the Red List of the International Union for Conservation of Nature (IUCN).
Sites at which manta rays congregate attract tourists, and manta viewing generates substantial annual revenue for local communities. Tourist sites exist in the Bahamas, the Cayman Islands, Spain, Fiji, Thailand, Indonesia, Hawaii, Western Australia and the Maldives.
Due to their size, it is rare for mantas to be kept in captivity and few aquariums currently display them.
The name “manta” is Portuguese and Spanish for mantle (cloak or blanket), a type of blanket-shaped trap traditionally used to catch rays.
The ancient Peruvian Moche people worshipped the sea and its animals. Their art often depicts manta rays.
Historically, mantas were feared for their size and power. Sailors believed that they ate fish and could sink boats by pulling on the anchors.
Mantas are known as “devilfish” because of their horn-shaped cephalic fins, which are imagined to give them an “evil” appearance.
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