Giant manta ray (Manta birostris)

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Giant manta ray with cephalic lobes furled, ventral view
IUCN Red List species status – Vulnerable VULNERABLE

Top facts

  • The giant manta ray is the largest ray species in the world.
  • The giant manta ray has the largest brain of all the world’s fishes, and much remains to be discovered about its intelligence and social interactions.
  • Despite its massive size, the giant manta ray feeds on some of the tiniest organisms in the ocean.
  • Giant manta rays often jump clear of the water, possibly as a form of communication or even play.
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Giant manta ray fact file

Giant manta ray description

KingdomAnimalia
PhylumChordata
ClassChondrichthyes
OrderRajiformes
FamilyMobulidae
GenusManta (1)

The largest living ray (1) and one of the largest of all elasmobranchs (4), the giant manta ray (Manta birostris) is a stunning and graceful member of the devil ray family (Mobulidae). This giant fish is notable for its sheer size, with anecdotal reports of individuals measuring up to 9.1 metres across (1) (2) (4).

The giant manta ray has a distinctive body shape, with triangular pectoral ‘wings’ and paddle-like lobes extending in front of the mouth (4) (5). Known as ‘cephalic lobes’, these are forward extensions of the pectoral fins which form a funnel-like structure while feeding, helping to channel plankton-filled water into the mouth (3) (4) (5). The lobes are rolled into a spiral when the giant manta ray is swimming (5).

The broad, disc-like body of the giant manta ray is just over twice as wide as it is long (2), and there is a small dorsal fin on the back (5), with a rudimentary spine immediately behind it, on the upper side of the tail (2). The tail of the giant manta ray is slender and slightly flattened (2) (5), and is shorter than the width of the disc-like body (5). The giant manta ray’s eyes are located on the sides of its head, and its gills are on the underside of the body (5). The cavernous mouth is positioned at the front of the head and has rows of tiny, peg-like teeth on the lower jaw (2) (4) (5).

The colouration of the giant manta ray can be quite variable. Most individuals belong to a ‘chevron morph’, which is predominantly black above and white below, with large white ‘shoulder’ patches on the back (2) (3). These conspicuous white patches occur on either side of a dark midline, and are more or less triangular or chevron-shaped, with hook-like extensions to the sides. There may also be small patches of white on the tips of the pectoral fins (2).

The underside of the giant manta ray is largely cream to white, with varying degrees of dark spots and patches, mainly on the belly (2) (3). There is usually a prominent black, semi-circular mark behind the fifth gill slit on each side of the body, and the rear margins of the pectoral fins have dark shading (2). The giant manta ray also has dark colouration around and inside its mouth (2) (3).

The giant manta ray also occurs in a striking ‘black morph’, which is completely black above and mostly black below, except for a variably sized white area around the gills and belly (2) (3). Dark spots are often visible on this white patch. Nearly all-white individuals have also been documented (2). Each giant manta ray possesses a unique pattern of blotches, spots and scars that can be used to identify individuals (3) (4) (5).

Manta rays were previously considered to be a single species, but have recently been split into two separate species based on differences in size, appearance, habitat and behaviour (1) (2) (3). The giant manta ray grows larger than the reef manta ray (Manta alfredi), and also has a non-functional tail spine, which is absent in the reef manta ray. The white shoulder patches of the reef manta ray form a ‘Y’ shape and gradually fade into the black of the back, whereas those of the giant manta ray form a ‘T’ shape and are clearly distinct from the black back. Reef manta rays also differ in having a white to grey rather than dark mouth, and the dark spots on their underside are more extensive (2) (3).

Studies have suggested that there may be a third species of manta ray, but more evidence is needed before the species are split further (1) (2).

Also known as
Atlantic manta, chevron manta, chevron manta ray, devil fish, devil ray, devilfish, devil-ray, giant devil ray, giant oceanic manta ray, manta, manta ray, oceanic manta, oceanic manta ray, Pacific manta ray, pelagic manta, pelagic manta ray.
Synonyms
Brachioptilon hamiltoni, Manta hamiltoni, Raja birostris.
Spanish
Manta Diablo, Manta Gigante, Manta Voladora.
Size
Disc width: up to 7 m (2) (3)
Weight
up to 2 tonnes (3)
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Giant manta ray biology

An exceptionally graceful swimmer, the giant manta ray almost appears to fly through the water using its large pectoral fins (4) (5). This species is capable of both rapid speed (4) and deep dives, sometimes reaching depths of over 1,000 metres (1). Giant manta rays have also been observed jumping clear of the water and landing with a loud splash, possibly as a form of communication or even play (4) (5).

Despite its enormous size, the giant manta ray feeds on tiny planktonic organisms by filtering large volumes of water through its mouth. Food is strained out of the water using plates of pinkish-brown, sponge-like tissue between the gills, known as ‘gill rakers’ (3) (4) (5). When feeding, the giant manta ray unfurls the fleshy cephalic lobes on either side of its head and uses them to direct water into the mouth (4) (5). It often swims in slow somersaults as it gathers food, or sometimes scoops plankton up along the sea bed (3) (4) (5).

The giant manta ray is thought to make seasonal migrations to take advantage of rich feeding areas (3) (4). Although it is generally solitary, loose aggregations may form where there is abundant food or for mating (1) (3) (4) (5). This species is often host to smaller fish called remoras, which attach to the manta ray’s body and consume particles of food that fall from its mouth. The giant manta ray regularly seeks out ‘cleaning stations’, where cleaner fishes such as wrasses (Labroides spp.) pick parasites off its body (3) (4) (5).

Courtship in the giant manta ray can last for days, with a number of males following a female around in a ‘mating train’, competing for the right to mate. Eventually, one of the males grasps the tip of the female’s pectoral fin in its teeth, and the pair mate belly-to-belly (3) (4) (5). As in other rays and sharks, fertilisation is internal, with the male transferring sperm to the female using a pair of ‘claspers’ on the inner part of the pelvic fins (4).

The developing eggs remain inside the female’s body for up to 12 months and then hatch internally, so that the female gives birth to live young (4). The female giant manta ray is believed to give birth to one or occasionally two young (1) (3) (4) (5), probably in shallow water and at night (3) (4) (5). Births may take place only once every two to five years (3). The newborn giant manta ray measures an impressive 1.2 to 1.5 metres across (3) (4), and may double in size during the first year of its life (4).

The giant manta ray is believed to mature at a disc width of about 4 to 4.5 metres in males and 5 to 5.5 metres in females (4) (5). This species is thought to be long-lived, with an estimated lifespan of at least 40 years (1). The only known predators of the giant manta ray are large sharks (1) (3) (4) (5), orcas (Orcinus orca) and false killer whales (Pseudorca crassidens) (3).

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Giant manta ray range

The giant manta ray is found in tropical, sub-tropical and temperate waters in all the world’s major oceans (1) (2) (3), between about 31 degrees North and 36 degrees South (3). It has been recorded as far north as southern California and New Jersey in the United States, Mutsu Bay in Japan, the Sinai Peninsula in Egypt and the Azores Islands, and as far south as Peru, Uruguay, South Africa and New Zealand (1) (2).

This species is believed to have a wider distribution than the closely related reef manta ray, and is more migratory in its behaviour (1) (3).

See this species on Google Earth.

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Giant manta ray habitat

A more oceanic species than the reef manta ray (1), the giant manta ray is thought to travel vast distances across the open ocean (3). It appears to be a seasonal visitor to coastal and offshore sites, and is commonly seen along productive coastlines with regular upwellings, as well as around oceanic islands, offshore pinnacles and seamounts (1) (2) (3).

The giant manta ray often visits shallow reefs to feed and to be cleaned by ‘cleaner fishes’ (1) (3).

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Giant manta ray status

The giant manta ray is classified as Vulnerable (VU) on the IUCN Red List (1).

IUCN Red List species status – Vulnerable

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Giant manta ray threats

The giant manta ray has been traditionally harvested for its oil-rich liver and for its skin (3) (5). It was formerly harvested commercially around eastern Australia and in the Sea of Cortez, Mexico, causing large declines in its populations (3) (4) (5).

Although it is sometimes taken in local fisheries for food and other products (1), the giant manta ray has more recently become highly valued in international markets for its gill rakers, which are used in the Chinese medicine trade (1) (3). In addition, the giant manta ray is often caught accidentally in other fisheries or becomes entangled in fishing lines or nets (1) (3) (4), including bather protection nets used for shark control (1).

The giant manta ray’s large size, slow swimming speed and tendency to be found at the water’s surface, often in well-known aggregation sites, make it relatively easy to catch (1) (3). Its slow birth rate also means that it is particularly vulnerable to unsustainable fishing and is slow to recover from any population declines (1) (3) (4).

Other potential threats to this giant fish include pollution, the degradation of its habitat, ingestion of plastic particles, collisions with boats and the effects of climate change (1). In addition, there are fears that increasing dive tourism could have negative effects on giant manta rays and their habitats if not properly regulated (1) (3) (4) (5).

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Giant manta ray conservation

Although international protection for the giant manta ray is still poor (3), a number of countries have established legal protection for this iconic species in their own waters. For example, manta rays are now legally protected from fishing around Hawaii, Mexico, the Philippines, Ecuador and New Zealand, while the Maldives have a complete export ban on all ray species (1) (3).

The giant manta ray is also listed on Appendices I and II of the Convention on Migratory Species (CMS), which aims to protect migratory species across their range (6). In the Maldives, two Marine Protected Areas have been set up specifically to help protect manta rays. There are also Marine Protected Areas around Mexico, although these may suffer from poor enforcement and threats from tourism (1) (3).

Dive tourism involving manta rays is a growing industry, and can potentially give the giant manta ray more economic value than the short-term profits from fishing. However, the industry needs to be appropriately managed to prevent harm to the giant manta ray or its habitat and to ensure that it remains sustainable (1) (3).

In 2011, the Manta Trust was formed to co-ordinate global research and conservation efforts for manta rays (3). Studies are underway to track the movement patterns of these ocean giants (4) (7), but further research is still needed into their biology, intelligence, social interactions and population sizes (3).

The splitting of manta rays into two distinct species will allow more appropriate management decisions based on differences in their behaviour, habitat use and life histories (2) (3). For example, national or regional fishing bans may protect the largely resident reef manta ray, but only provide temporary protection for the more migratory giant manta ray (3).

As large and charismatic species, manta rays may serve as a useful ‘flagship’ species for conservation, helping to promote the protection of the wider marine environment (3).

View information on this species at the UNEP World Conservation Monitoring Centre.
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Find out more

Find out more about the giant manta ray and other manta ray species:

More information on the conservation of sharks and rays:

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Authentication

Authenticated (31/08/12) by Josh Stewart, Associate Director, Manta Trust.
http://www.mantatrust.org/

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Glossary

Dorsal fin
The unpaired fin found on the back of the body of fish, or the raised structure on the back of most cetaceans (whales, dolphins and porpoises).
Elasmobranch
A member of a group of cartilaginous fish that includes sharks, skates and rays.
Fertilisation
The fusion of gametes (male and female reproductive cells) to produce an embryo, which grows into a new individual.
Morph
One of two or more distinct types of a given species, often distinct colour forms, which occur in the same population at the same time (that is, are not geographical or seasonal variations).
Parasite
An organism that derives its food from, and lives in or on, another living organism at the host’s expense.
Pectoral fins
In fish, the pair of fins that are found one on each side of the body just behind the gills. They are generally used for balancing and braking.
Pelvic fins
In fish, the pair of fins found on the underside of the body.
Plankton
Aquatic organisms that drift with water movements; may be either phytoplankton (plants), or zooplankton (animals).
Upwelling
The upward movement of cold, nutrient-rich water from the ocean depths, usually as a result of winds and currents.
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References

  1. IUCN Red List (June, 2012)
    http://www.iucnredlist.org/
  2. Marshall, A.D., Compagno, L.J.V. and Bennett, M.B. (2009) Redescription of the genus Manta with resurrection of Manta alfredi (Krefft, 1868) (Chondrichthyes; Myliobatoidei; Mobulidae). Zootaxa, 2301: 1-28.
  3. Manta Trust (June, 2012)
    http://www.mantatrust.org/
  4. Reef Quest Centre for Shark Research (June, 2012)
    http://www.elasmo-research.org/index.html
  5. Ichthyology Department, Florida Museum of Natural History - Manta (June, 2012)
    http://www.flmnh.ufl.edu/fish/Gallery/Descript/MantaRay/MantaRay.html
  6. Convention on the Conservation of Migratory Species of Wild Animals (June, 2012)
    http://www.cms.int/
  7. Graham, R.T., Witt, M.J., Castellanos, D.W., Remolina, F., Godley, B.J. and Hawkes, L.A. (2012) Satellite tracking of manta rays highlights challenges to their conservation. PLoS ONE, 7(5): e36834.
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Giant manta ray with cephalic lobes furled, ventral view   
Giant manta ray with cephalic lobes furled, ventral view

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