Oceanic Manta Ray

The giant oceanic manta ray can grow up to 9 m (30 ft) in length and a disc size of 7 m (23 ft) across, with a weight around 3,000 kg (6,600 lb), but the typical size is 4.5 m (15 ft). It is dorsoventrally flattened and has large, triangular pectoral fins on either side of the disc.

At the front, it has a pair of cephalic fins, which are forward extensions of the pectoral fins. These can be rolled up in a spiral for swimming or flared out to channel water into the large, forward-pointing rectangular mouth when the animal is feeding.

The teeth are in a band of 18 rows and are restricted to the central part of the lower jaw.

The giant oceanic manta ray has a widespread distribution in tropical and temperate waters worldwide. In the Northern Hemisphere, it has been recorded as far north as southern California and New Jersey in the United States, Aomori Prefecture in Japan, the Sinai Peninsula in Egypt, and the Azores in the northern Atlantic. In the Southern Hemisphere, it occurs as far south as Peru, Uruguay, South Africa, and New Zealand.

It is an ocean-going species and spends 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 found in association with offshore oceanic islands.

Males become sexually mature when their disc width is about 4 m (13 ft), while females need to be about 5 m (16 ft) wide to breed. When a female is becoming receptive, one or several males may swim along behind her in a "train". During copulation, one of the males grips the female's pectoral fin with his teeth and they continue to swim with their ventral surfaces in contact. He inserts his claspers into her cloaca, and these form a tube through which the sperm is pumped. The pair remains coupled for several minutes before going their own way.

The oceanic manta ray is considered to be endangered by the IUCN's Red List of Endangered Species because its population has decreased drastically over the last 20 years due to overfishing. Because M. birostris feeds in shallow waters, the risk of them getting caught in fishing equipment is higher, especially in surface drift gillnets and bottom set nets. Whatever the type of fishing (artisanal, targeted, or bycatch), the impact on a population with a low fecundity rate, a long gestation period with mainly a single pup at a time, and a late sexual maturity can only be seriously detrimental to a species that cannot compensate for the losses over several decades.