Megamouth Shark

Megamouth Shark
General information
Universe	Real Life
Classification	Megachasma pelagios
Species type	Planktivorous Shark
Homeworld	Earth
Environment	Deep sea
Intelligence	Non-Sapient
Biochemistry	Carbon-based lifeform
Biological information
Reproduction	Sexual; ovoviviparous birth
Average weight	1,215 kg (2,679 lb)
Average length	5.5 metres (18 ft)
Locomotion	Powered swimming
Feeding behavior	Carnivorous
Prey	Plankton
Lineage information
Related species	Basking Shark Whale Shark
Cultural information
Alignment	Neutral
Organization	Solitary
Sociocultral characteristics
Scientific taxonomy
Planet	Earth
Domain	Eukaryota
Kingdom	Animalia
Subkingdom	Eumetazoa
Infrakingdom	Bilateria
Superphylum	Deuterostomia
Phylum	Chordata
Subphylum	Vertebrata
Infraphylum	Gnathostomata
Class	Chondrichthyes
Subclass	Elasmobranchii
Superorder	Selachimorpha
Family	Megachasmidae
Genus	Megachasma
Species	pelagios
Other information
Status	Data Deficient

The megamouth shark (Megachasma pelagios) is an extremely rare species of deepwater shark, and the smallest of the three planktivorous sharks, besides the whale shark and basking shark. Since its discovery in 1976, few megamouth sharks have been seen, with 59 specimens known to have been caught or sighted as of June 2014, including three recordings on film. Like the other two filter-feeders, it swims with its enormous mouth wide open, filtering water for plankton and jellyfish. It is distinctive for its large head with rubbery lips. It is so unlike any other type of shark that it is usually considered to be the sole extant species in the distinct family Megachasmidae, though suggestion has been made that it may belong in the family Cetorhinidae, of which the basking shark is currently the sole extant member. In addition to the living M. pelagios, however, two extinct megamouth species – the Cretaceous M. comanchensis and the Oligocene–Miocene M. applegatei – have also recently been proposed on the basis of fossilized tooth remains.

Description

The appearance of the megamouth is distinctive, but little else is known about it. It has a brownish-black colour on top, is white underneath, and has an asymmetrical tail with a long upper lobe, similar to that of the thresher shark. The interior of its gill slits are lined with finger-like gill rakers that capture its food. A relatively poor swimmer, the megamouth has a soft, flabby body and lacks caudal keels.

Megamouths are large sharks, able to grow to 5.5 metres (18 ft) in length. Males mature by 4 m (13 ft) and females by 5 m (16 ft). Weights of up to 1,215 kg (2,679 lb) have been reported.

As their name implies, megamouths have a large mouth with small teeth, and a broad, rounded snout, causing observers to occasionally mistake megamouth for a young orca. The mouth is surrounded by luminous photophores, which may act as a lure for plankton or small fish. Their mouths can reach up to 1.3 m (4 ft 3 in) wide.

Behavior

In 1990, a 4.9-m (16-foot) male megamouth shark was caught near the surface off Dana Point, California. This individual was eventually released with a small radio tag attached to its soft body. The tag relayed depth and time information over a two-day period. During the day, the shark swam at a depth of around 120–160 m (400–525 ft), but as the sun set, it would ascend and spend the night at depths of between 12 and 25 m (39–80 ft). Both day and night, its progress was very slow at around 1.5–2.1 km/h (1–1.3 mph). This pattern of vertical migration is seen in many marine animals as they track the movement of plankton in the water column. The shark captured in March 2009 was reportedly netted at a depth of 200 m (660 ft).

Reproduction

Reproduction is ovoviviparous, meaning that the young sharks develop in eggs that remain within the mother's body until they hatch.