Common
Names: Manta
Ray, Pacific or Atlantic Manta ray, Devil ray.
Latin
Name: Manta
birostris
Family:
Mobulidae
Identification:
Immense
size (the largest of all the rays). Terminal mouth has well developed, flexible
cephalic fins. Dorsum black or dark often with symmetrical white patches forming
a chevron across the shoulders. Wing tips also often fade to white. Ventrum
white or pale often with dark symmetrical patches. Single dorsal fin anterior to
tail. Tail thin and less than body length
Size:
Maximum
width 6.7m. Disc width at birth 1.2m. Unsubstantiated reports stretch up to 9m.
Habitat:
Oceanic
offshore waters. A regular visitor to sea mounts and off shore islands where
plankton is forced to the warmer surface layers.
Abundance
and distribution: Circumtropical and less commonly circumtemperate. I
have one report from as far north as Vancouver island in Canada from the
1960's.
Behavior: Usually
seen where plankton is concentrated. Unrolls
its cephalic fins and uses them as a scoop for funnelling plankton. Sometimes
somersaults in the water column when feeding. May breach perhaps to rid itself
of parasites. Seen singly or in
aggregations where food (plankton) is abundant.
"Warm blooded" i.e. able to control its body
temperature relative to that of the waters in which it feeds. This may be a tool
for maintaining constant muscle function whilst moving in and out of
thermoclines. Has been known to travel long distances and congregate for coral
or fish spawning.
Reproduction:
Ovoviviparous.
Gives birth to one or two pups.
Observations: Often
has a remora above and behind each eye.
Photographs:
Koh
Bon, Koh Similan (Thailand).
Similar
species:
Manta birostris was once thought to be split into regional subspecies but the
genus has been revised to include just the one species. Manta populations may
have regionally consistant markings.
Reaction
to divers: Curious,
often approaching divers and in some areas allowing contact (belly rubbing)
which it seems to enjoy. Will sometimes play (somersault) in the divers bubbles.
Moves
away when pursued. Will tolerate riding for short periods but this behaviour
from divers is not encouraged! Mantas come to plankton rich seamounts to feed
and if stressed and forced to leave this impacts on their ability to get the sustenance
they need.
Diving logistics: This
is a commonly seen ray in various locations around the tropics. It can be
seasonally encountered by divers in the many areas but places in which mantas
are specifically sought after include the Andaman sea islands of Thailand (from
Hin Maeng to Burma). Yap and Palau, Hawaii, Sea of Cortez, and many other
places. In Thailand day trip or live-aboard dive vessels take divers out of
Phuket to reach these islands. Whale sharks enjoying the same seasonal food
source are sometimes jointly encountered.
Other diving locations submitted by readers:
Further
reading:
Reef
Sharks and Rays of the World. Scott W. Michael. Sea Challengers.
Sharks
and Rays - Elasmobranch Guide of the World. Ralf M. Hennemann. IKAN.
