The manta ray, or giant manta (Manta birostris), is
the largest of the rays, ranging up to 6.7 meters (22 ft) across
its pectoral fins (or "wings") and weighing up to 1,350
kg (3,000 lb). It ranges throughout the tropical seas of the world,
typically around coral reefs. Mantas are most commonly black above
and white below, but some are blue on their backs. A giant manta's
eyes are located at the base of the cephalic fins on each side of
the head, and unlike other rays the mouth is found at the anterior
edge of its head. To breathe, the manta has like other rays five
pair of gills on the underside.
With distinctive "horns", or "cephalic fins",
on either side of its broad head, the manta is a prized sighting
by divers. These unique horns are actually structures made by the
pectoral fins where a part breaks off during the embryological stage
and moves foreward and surrounds the mouth, which makes them the
only known example where jawed vertebrates have evolved novel limbs
(the so-called six-footed tortoise (Manouria emys) has of course
not actually six legs, only enlarged tuberculate scales present
on their thighs that looks a bit like an extra pair of hind limbs).
These flexible horns are also called cephalic fins and are used
to direct plankton and water into their very broad and wide mouth.
To make them more streamlined when swimming, they are able to curl
They evolved from bottom feeders a long time ago, but later adapted
to become filter feeders in the open ocean. This has allowed them
to grow to a size larger than any other species of rays. Because
of their pelagic lifestyle as plankton feeders, some characterstics
have been degenerated. All that is left of their oral teeth is a
small band of vestigial teeth on the lower jaw, almost hidden by
the skin. They are closely related to stingrays, but they don't
have any stinger. Also their dermal denticals are greatly reduced
in number and size, but are still present, and they have a much
thicker body mucus coating than other rays. Their spiracles have
become small and non-functional, all the water is taken in through
their mouth instead.
To better swim through the ocean, they have evolved a diamond shaped
body plan, using their pectoral fins as graceful "wings".
Mantas generally eat plankton, fish larvae and small organisms
that are filtered out from the water by their gill rakers, a type
of filter feeding that is called ram-jet feeding.
Taxonomically, the situation of the mantas is still under investigation.
Three species have been identified: Manta birostris, Manta ehrenbergii,
and Manta raya, but they are quite similar to each other, and the
last two may just be isolated populations. The genus Manta is sometimes
placed in its own family, Mobulidae, but this article follows FishBase,
and places it in the family Myliobatidae, with the eagle rays and
Mantas have been given a variety of common names, including Atlantic
manta, Pacific manta, devil ray, devilfish, and just manta. Some
people just call all members of the family stingrays.
Mantas have recently been captured on film while breaching. This
had been reported in the past, but without any conclusive evidence.
In the last few years, sharks have also been photographed while
leaping out of the water. As with sharks, the reason for this behavior
in rays is currently unknown, though may be to dislodge loose dead
skin & parasites when impacting back on the water.
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