Mantas are the largest of the rays and can grow to a wingspan of over twenty feet
(7 m) and to a weight of more than three thousand pounds (1350 kg).
Apart from size, the most noticable difference between mantas and most
other rays are the "cephalic fins"
extending forward from the eyes, sometimes carried rolled up. Unrolled,
these distinctive fins are said to be used to guide masses of plankton into
its mouth, which is in front of its body rather than underneath it.
Mantas have a highly developed branchial sieve which retains any small organisms
taken in with the water through the mouth.
Mantas are probably circumtropical but their actual range and number is
poorly understood, even today. In the West Atlantic, mantas have been recorded
from New England and Bermuda to Brazil, including the Gulf of Mexico.
Mantas are dark brown to black on top with paler margins and
are primarily white underneath.
Individuals may have whitish patches of various sorts and patterns on top and
may have irregular and variable gray or black botches underneath.
Mantas are pelagic, that is they live in the open ocean,
but, luckily for divers, they do frequent coastal waters as well.
Mantas seem to spend a great deal of time at or near
the surface, either swimming by flapping motions of their hugh wing-like pectoral fins
or just drifting, sometimes with their wing-tips extended up and out of the water.
Mantas are known to leap from the water, sometimes even somersaulting, and then
fall back with a large splash. This has been thought to be either a way to remove
irritating parasites or simply playful occupation, perhaps both.
Remoras (Echeneida) are frequently associated with mantas and have been observed
in and around the mouth, clinging to forward portions of the pectoral fins, and
even inside the gill cavities. It is thought that these remora feed on parasites from
the manta's body and perhaps even on the plankton as well.
Mantas have live births, and, in all recorded cases, have had only a single embryo.
Embryos weighing twenty pounds and over fifty inches (1.4 m) wide have been reported,
but normal newborn mantas are thought to be slightly smaller than this.
Although Devil Rays (Mobula hypostoma) are quite similar, mantas can be
distinguished from them by the position of the mouth, the shape of the pectoral fin,
and the fact that normal Devil Rays rarely exceed the size of a large manta newborn
(4 ft; 1.3 m).
In the spring and summer of 1991, a juvenile female manta with a wingspan
of approximately 10ft (3 m), later to be named
Molly,
first started showing up in Little Cayman.
Appearing during night dives at Bloody Bay, and apparently
feeding off the plankton in the water attracted by the dive lights,
Molly would sweep in and through the groups of divers to the thrill of all.
At first primarily a summer resident, during the past few years Molly could be seen
out on the south coast flats during the winter months as well.
Unfortunately, Molly has not been seen regularly since 1995. Reaching sexual
maturity and now most likely off to search for a mate, Molly has left behind
many broken hearts.
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