Legend-islands : Guide for wayfaring travelers: Diving with Manta Rays

Family name: Myliobatidae, subfamily Mobulinae
Order name: Batoides
Common name: Mantaray
Scientific name: Manta Birostris (Dondorff, 1798)

The Spanish word for blanket is 'manta' and aptly describes the unique spherical body shape of this animal. Also known as "devil ray" with graceful pectoral 'wings', manta rays are easily recognised by their paddle-like cephalic lobes projecting forward from the front of the head (actually extensions of the pectoral fins, supported by radial cartilages), and a very broad, rectangular terminal mouth.

The manta ray, or giant manta (Manta birostris), is the largest of the rays, with the largest known specimen having been nearly 7.6 meters (25 ft) across its pectoral fins (or "wings") and weighed in at 3,000 kg (6,600 lb). Mantas vary in colour from black, grey-blue, to red-brown on the upper surface of their cartilage body, sometimes with white shoulder patches and blotches, and almost pure white on the lower surface of their pectoral fins and body disc. Their body patterns show individual variation and helps identify individuals. There are also regional differences in manta ray colour patterns. For example, specimens from the eastern Pacific often feature dusky to mostly black undersurfaces, while those from the western Pacific are typically snow white underneath.

Although it's difficult not to recognise an adult manta ray, juveniles are similar to mobula rays (of which there are nine species) that grow to three metres and share paddle-shaped cephalic lobes and gracefully curved pectoral wings. Mantas are now thought to be a single species, and mobulas are most readily distinguished by the position of the mouth - mantas have terminal mouths (located at the front of the head), whilst mobulas have sub-terminal mouths (located underneath the head, similar to many sharks).

Even though manta rays have up to 300 rows of small peg shaped teeth (the size of pin heads) only on the lower jaw, they really are gigantic filter-feeders, preying on planktonic crustaceans and small schooling bony fishes. The two fleshy lobes of cephalic fins are unrolled and held at a downward angle to create a funnel guiding prey into their enormous mouth. Feeding often occurs near or at the surface where plankton accumulates.

The mantaray are ovoviviparous with a usual litter size of two - each pup wrapped in a thin-shell that hatches inside the mother, later to be born alive. Birth occurs in relatively shallow water, where the young remain for several years before expanding their range further offshore. Like sharks and other rays, mantas are fertilized internally. Male manta rays have a pair of penis-like organs called claspers, along the inner part of their pelvic fins. During courtship, male chase the female, eventually one grasping the tip of one of her pectoral wings between his teeth, and pressing his belly against hers. Then, the male flexes one of his claspers and inserts it into her vent. Copulation lasts about 90 seconds. The fertilized eggs develop inside a mother manta's body for an unknown length of time that may exceed 12 months.

A newborn manta ray is about 125cm wide and growth is rapid, doubling in size during the first year of life. Males mature when they reach a size of about four metres, females at about five metres; it is unknown what age this is. Likewise, it is not known how long mantarays live, but best guesses are about 25 years.
Only large warm water sharks, such as the tiger shark are known to prey naturally upon manta rays.

Manta ray distribution is circum-tropical, around the globe, generally between 35 degrees north and south latitude, including South Africa, Madagascar, Mozambique to Somalia; in the Gulf of Aden, Red Sea, Arabian Sea, the Bay of Bengal, Burma (Myanmar), Thailand, Malaysia, Indonesia, Philippines, Cambodia to southern Japan; northern Australia, Micronesia, New Caledonia, Fiji, New Guinea, Solomon Islands, Hawaii; southern California to northern Peru, North Carolina to southern Brazil, the Azores, and Senegal to Liberia.