Spinetail mobula (Mobula japanica)

Also known as: devilray, Japanese devilray, spinetail devilray
French: Mante Aguillat
Spanish: Manta De Espina, Mante De Aguijón
GenusMobula (1)
SizeMale disc width: up to 310 cm (2) (3)
Female disc width: up to 240 cm (2)
Disc width at birth: c. 85 cm (3) (4)
Adult weight: c. 115 kg (5)

The spinetail mobula is classified as Near Threatened (NT) on the IUCN Red List (1).

The spinetail mobula (Mobula japanica) is a large and graceful ray, with a very long, whip-like tail, which has a sting at the tip, a spine at the base and a row of small white ‘teeth’, known as denticles, along each side (3) (4) (5) (6) (7). The upperside of the body is dark blue or black, with slit-like spiracles and white areas behind the eyes (2) (4) (6). The body of all Mobula species is flattened into a disc that is much wider than it is long and is rhomboid in shape (7). Small denticles are present on the upperside of the disc, as well as on the cephalic fins, lower jaw, gills, abdomen and the underside of the pelvic fins (6).

The underside of the spinetail mobula is white, and features two cephalic fins, one on either side of the mouth (2) (5). The cephalic fins protrude forwards and are silver-grey on the inner surface with black tips (2) (6). The mouths of Mobula species have teeth in both jaws (5) (7).

Juvenile and newborn spinetail mobulas have white shoulder patches (3).

The spinetail mobula is found in the warm temperate and tropical waters of the Pacific and Atlantic Oceans (1) (2) (3) (4) (6). The southern Gulf of California is thought to be an important feeding and mating area for adult spinetail mobulas (1).

The presence of this wide-ranging fish in the northern and western Atlantic Ocean is unconfirmed (1) (6), and its range may be more extensive than is currently known (2).

The spinetail mobula occurs in both inshore and offshore waters and is usually found close to the surface of the water (3) (4).

The diet of the spinetail mobula is mostly composed of plankton, krill and other euphausiids such as Nictiphanes simplex, although copepods, small fishes and crustacean larvae are also occasionally taken (1) (2) (3).

The spinetail mobula may occur both singly and in small groups, but is not thought to form large schools (1) (2) (3) (4). In certain areas, the spinetail mobula mates in spring and summer, after which the female gives birth to a single litter (3) containing one pup (1). This species is ovoviviparous, meaning that the eggs hatch inside the female’s body and the young are born live (2). The female has just one functional ovary and during the first stage of internal development, the embryo is initially enclosed within an egg and nutrients are gained from the yolk sac. After hatching from the egg inside the female, the embryo continues to develop and obtains its required nutrients from the fluid in the female’s uterus until the pup is born live (1). 

The spinetail mobula is commonly caught as bycatch by the fishing industry throughout its range. It is also caught purposefully in Indonesia, Mexico, the Gulf of California and the Philippines, where it is used for its gills, cartilage, skin and meat (1) (2).

The slow reproduction of the spinetail mobula puts it under particular threat from overfishing, while unsustainable fishing practices may be reducing its worldwide population size (1).

More research is needed into the biology of the spinetail mobula to assess the extent to which fishing poses a threat to its population size. Legislation is being introduced in Mexico to establish an elasmobranch fishery management programme, and improving recorded catches of the spinetail mobula would help identify fluctuations in catch and fishing effort (1).

In the Philippines it is currently illegal to fish for any Mobulidae species, although enforcement is inadequate and illegal fishing is still thought to occur. Immediate conservation measures must be implemented to manage the trade and harvest of this unique species (1).

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  1. IUCN Red List (April, 2012)
  2. FishBase - Spinetail mobula (March, 2012)
  3. Michael, S.W. (2005) Reef Sharks and Rays of the World: A Guide to Their Identification, Behaviour, and Ecology. ProStar Publications, Maryland.
  4. Bonfil, R. and Abdallah, M. (2004) Field Identification Guide to the Sharks and Rays of the Red Sea and Gulf of Aden. Food and Agriculture Organization of the United Nations, Rome. Available at:
  5. Eschmeyer, W.N., Herald, O.W., Mammann, H. and Gnagy, J. (1983) PacificCoastFishes. Houghton Mifflin, New York.
  6. Smith, M.M. and Heemstra, P.C. (1986) Smith’s Sea Fishes. Macmillan South Africa, Johannesbourg.
  7. Paulin, C.D., Habib, G., Carey, C.L., Swanson, P.M. and Voss, G.J. (1982) New records of Mobula japanica and Masturus lanceolatus, and further records of Luvaris imperialis (Pisces: Mobulidae, Molidae, Louvaridae) from New Zealand. New ZealandJournal of Marine and Freshwater Research, 16: 11-17.