Manta Rays and you!
Here is a lot more information about Manta Rays. These guys are really cool. More than that, they are majestic – no other word for it. They move so smoothly and such grace.
Sitting in currents that knock us about like rubber ducks, the Manta will just glide right by with barely a flick of its wing.
While they don’t have a “season” here on the Similans, they do tend to be encountered most frequently in February and March.Still we see them throughout the year and at almost all dive sites. The odds are highest for encounters at Koh Bon and Koh Tachai. But we have seen them at almost every site on the Similans at some point – diving or snorkeling.
If this doesn’t some of your safety questions – please look at our other Similan Island Manta Ray postings. We also visit these sites for diving and snorkeling if you would like to experience this for yourself.
| Recognition | A gigantic devilray with gracefully sculpted, falcate pectoral ‘wings’, 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 mouth at the end of the head (a mouth type known as ‘terminal’), pebble-like teeth in the lower jaw but not the upper. They don’t have teeth in the traditional sense. |
| Color | Variable, ranging from black, greyish blue, to greenish or reddish brown above (black color morph sometimes with whitish, triangular shoulder patches), and nearly black, white with various degrees of greyish blotching (the precise pattern of blotching has been used to identify individuals), to almost pure white below; one albino specimen has been reported. |
| Size | Disc width at birth about 4 feet (1.2 metres); maximum disc width 22 feet (6.7 metres), possibly larger (reported to widths of up to 30 feet or 9.1 metres), maximum recorded weight 3 100 pounds (1 400 kilograms). Click here for amazing birth video… |
| Distribution | Circumtropical (around the globe, generally between 35 degrees north and south latitude), including: off southeastern South Africa, Madagascar, Mozambique, Tanzania, Kenya, and Somalia; in the Gulf of Aden, Red Sea, Arabian Sea, and the Bay of Bengal, off Burma (Myanmar), Thailand, Malaysia, Indonesia, northern Australia, New Guinea, Solomon Islands, Philippines, Kampuchia, Viet Nam, China, Korea, and southern Japan; off Guam, Palau, Yap, New Caledonia, Fiji, and Hawaii; off southern California to northern Peru, North Carolina to southern Brazil, the Azores, Senegal to Liberia. |
| Habitat | Occurs most often in nearshore waters (mainly over continental and insular shelves, but occasionally over deep water), near coral and rocky reefs; swim by flapping their large pectoral fins and are usually encountered near the surface or mid-waters of lagoons or seaward reefs, particularly near surge channels; in Australian waters, Mantas sometimes migrate into temperate waters; they are capable of rapid speed and juveniles sometimes leap well clear of the water, landing with a loud slap (adults drive their bodies only partway out of the water and then fall back into the sea, sometimes performing 2 or 3 of these jumps in succession); often host to one or more discfishes (especially the White Remora, Remorina albescens) and sometimes observed in association with dolphins, seabirds, sharks, and other rays (notably the Spotted Eagle Ray, Aetobatus narinari); these rays actively seek the services of cleaner wrasses (Labroides spp.), often hanging over or swimming near “cleaning stations”, sometimes several lining up to wait their turn. |
| Feeding | A gigantic filter-feeder, preying on planktonic crustaceans and small schooling bony fishes; filtering mechanism consists of transverse plates of pinkish-brown spongy tissue that bridge the gaps between successive gill bars (cartilaginous skeletal elements that support the gills); when feeding, the cephalic lobes are unfurled and spread (directing and sometimes apparently scooping plankton-bearing water into the mouth), the animal often swimming in slow somersaults (vertical loops) that are repeated over and over (this behavior may keep the rays within a patch of particularly rich feeding, and may also concentrate planktonic prey to facilitate feeding); most often encountered as solitary individuals, but members of this species often aggregate in regions offering predictably rich feeding (off Yap, in the western Caroline Islands) — with up to 50 individuals clustered in the same general area, but not forming true schools. The geology of Koh Bon ridge is particularly conducive to these habits. Sadly we only groups of 5 or 6 |
| Reproduction | Ovoviviparous, with each of the pups wrapped in a thin-shell that hatches inside the mother, later to be born alive; one specimen harpooned off North Carolina expelled a pup (with one pectoral fin wrapped above its body, and the other wrapped below) in mid-trajectory when it leaped, a behavior which may represent spontaneous abortion (ejected prematurely due to capture stress) or be part of normal birthing (If so, what a dramatic way to enter the world!); litter size 1 to 2 (usually 2) pups, with birthing apparently occur in relatively shallow water, where the young remain for several years before expanding their range farther offshore; mating behavior in this species has recently (July 1997) been filmed off the Ogasawara Islands, Japan, and featured one or more males rapidly chasing a female for 20—30 minutes, after which one male nips the tip of either of the female’s pectoral fins (which severely impairs her swimming), moves to her ventral surface, and inserts one of his claspers (paired intromittant organs, developed along the inner margins of the pelvic fins) into her cloaca (vent), thereby mating belly-to-belly; the male may hold onto the (much larger) female’s pectoral fin for several minutes after removing his clasper, eventually letting her go free. |
| Age & Growth | Growth of newborns is apparently very rapid, virtually doubling the disc width at birth during the first year of life; males may mature at a disc width of about 13—15 feet (4.0—4.5 metres), females at a disc width of about 16—18 feet (5.0—5.5 metres), but this needs confirmation; no data on age at maturity for either sex. |
| Danger to Humans | Minimal unless attacked (especially harpooned) or otherwise startled, but the enormous size and power of this ray should invite respect. Not only is there a danger from any contact (don’t try to touch 1 tonne animals in the wild) but actually trying to ride one brings huge consequences in many ways. DON’T Touch them |
| Utilization | Formerly hunted commercially by harpoon from small boats off eastern Australia and in the Sea of Cortez (Gulf of California), this species is now rarely hunted; places where these rays can be reliably encountered have spawned substantial dive-tourism industries; seemingly inquisitive, individual Mantas sometimes approach and even solicit attention from divers, apparently enjoying the tactile stimulation provided by the bubbles from scuba exhaust; in areas frequented by divers, however, Mantas often become very wary of divers and cease to approach them. When approached rapidly, some individuals roll onto their backs (perhaps to keep the offending diver in sight?), sound (dive), and swim away rapidly, righting themselves only when some distance away; another behavioral response to approach by a diver from the side is curving one pectoral fin toward its back and the other toward its belly — forming an S-shape in cross-section — tilting its dorsal (top) surface toward the diver (possibly a defensive response?); in areas where divers touch Mantas, the rays often develop pinkish skin lesions that may persist for months (apparently these lesions occur where human touch has removed the protective mucus that coats the rays’ skin). When diving or snorkeling with these magnificent, supremely graceful rays, resist the temptation to touch them and avoid obstructing their looping glide path while they feed. Not only bearing in mind the currents that they usually associate themselves with, it’s also a great idea to neither pursue nor intrude on thier path. They frequently return to the same spot. Patience is the key to encounters with these magnificent creatures |
| Remarks | The Manta Ray is one of the very largest and least-known elasmobranchs; although stingless, Manta Rays are actually very closely related to stingrays (family Dasyatidae), the Manta Ray, together with 9 species of devil rays (genus Mobula) comprising a subfamily (Myliobatinae) within that group; until recently, a number of Manta species were considered valid (Manta alfredi, M. ehrenbergi, M. hamiltoni), but all are now tentatively regarded as a single, world-wide species; this matter is currently under investigation by comparison of genetic samples from several populations, which should (hopefully) settle the matter once and for all. |
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