Good heavens! This is a big 'un!
Source:
https://www.sharks-world.com/megamouth_shark/
Megamouth Shark – Megachasma pelagios
The megamouth shark is an exotic species discovered in 1976. It is
very unlikely to see, and no one suspected its existence until then,
when a new family, genus, and species was created to classify this
shark.
It is the most primitive living species of the order Lamniformes but
is the smallest shark of those that feed on plankton. He is a member of
the mentioned order, the family, Megachasmidae, and the genus
Megachasma.
DESCRIPTION
Its large head and the huge mouth that indicates its name are the
main features that help to identify this species undoubtedly. It has a
length of 4 – 5 meters and weighs about 800 kilograms. The color of its
cylindrical and flaccid body is usually black or dark brown on the
dorsal area and pale gray in the ventral region. Its skin also has
dermal denticles as other shark species.
It is the most primitive living species of the order Lamniformes.
It is not a skilled swimmer. Their dorsal fins are small and the
second is half the size of the first one. It has pectoral fins smaller
than the size of its head, and it has an asymmetrical caudal fin with a
long upper lobe.
It has tiny eyes, five pairs of long gill slits, and a short, rounded
snout. Inside the mouth has a tongue covered with mucosa and about 50
rows of small hooked teeth but only uses the first three rows. Around
its mouth, it has photophores which glow and appear to act as baits for
small fish or plankton.
DISTRIBUTION AND HABITAT
Its distribution and habitat are still uncertain, but a few sightings
in areas of the Pacific, Indian and Atlantic Oceans are on record; and
since its discovery in Hawaii, only 55 more sightings have been
registered in countries such as Brazil, Senegal, the Philippines and
Indonesia. The first discoveries were on the coasts of California,
Japan, and Australia, in addition to the Hawaiian islands.
It is an inhabitant of the deep waters (between 150 and 1,000 meters) that likes moderate and warm temperatures.
FEEDING
It is one of the three species of sharks that are fed by filtration
of plankton. Its diet may include shrimp, copepods, and pelagic
jellyfish.
There are few details about its form of feeding, but most scientists
think that it swims slowly through the plankton concentrations and opens
its huge mouth to suck the water, then lower the jaws, retract and
filter the planktonic organisms by expelling the water through its
gills.
BEHAVIOR
The limited observations of this shark provide little information but
render an overview. It is known to exhibit a behavior similar to that
of other benthic fishes, and it does not tolerate the disturbances
external to the ocean, perhaps that is the reason for its late
discovery.
This shark is a vertical migrant during 24-hour cycles.
In the early 1990s, a tag was placed on megamouth shark to monitor
for two days its behavior in the coasts of California, United States. As
the sun start shining, it swam to a depth of 120-160 meters but began
to ascend as the sun began to hide. During the night it stayed near the
surface at depths between 12 and 25 meters. The research gave evidence
that this shark is a vertical migrant during 24-hour cycles, spends days
in deep water and nights in mid-depth waters.
Probably, this pattern of movement is related to the behavior in the
columns of water of his favorite prey, which he follows to feed on.
REPRODUCTIVE HABITS
Sexual maturity occurs when the shark reaches a length of about 4
meters. Fertilization is internal, so the male inserts its claspers into
the female oviduct to transfer the sperm.
The megamouth shark is an ovoviviparous species. Therefore the pups
are developed inside the mother’s body until their birth. The genders
separate and look the same as adults.
The ovaries of the female are similar to those species that practice
oophagy, and this means that presumably the offspring of this shark also
feed on other eggs inside the body of their mother.
THREATS AND CONSERVATION
The fact that this shark is hard to observe implies a problem in its
research and the detection of the type and severity of its threats. In
fact, the International Union for the Conservation of Nature does not
yet have enough data to classify this species.
So far, its greatest threat is bycatch resulting from commercial
fishing activities. On the other hand, some museums welcome deceased
individuals for its exhibition. So far proper conservation measures have
not been taken.
:o)