Megachasma pelagiosMegamouth shark

Geographic Range

The Megamouth Shark was recently discovered in deep water off of the Hawaiian Islands and near the shores of California, Japan and Western Australia.

Habitat

The megamouth lives in the deep scattering layer of the ocean. It seems to enjoy warmer climates, though it has been discovered in temperate waters.

Physical Description

The megamouth Shark is five meters long and weighs approximately 750 kilograms. Its body is cylindrical and flabby, its eyes small, and it swims in stiff, slow movements.

  • Average mass
    750 kg
    1651.98 lb

Reproduction

The megamouth reproduces sexually through internal fertilization. There are separate sexes, and the offspring are miniature versions of the adult at birth.

Behavior

This shark behaves similarly to the fish of the deep scattering layer. It migrates vertically during a twenty-four hour cycle, swimming at depths of 200 meters below the surface by day, and ascending to 10-15 meters below the surface by night. It flees from minute disturbances into deep depths, which may explain why this species remained undiscovered for so long.

Food Habits

The Megamouth is a filter feeder. It uses its enormous mouth to draw in water and filter out small planktonic animals such as crustaceans and shrimp.

Economic Importance for Humans: Positive

Little is known about the economic importance of the megamouth shark, though sharks in general have proven to be an essential element in the aquatic ecosystem. In areas where sharks were killed because of the belief that they threatened fisheries by preying on certain fish, a significant disruption of the ecosystem (such as overpopulation of small fish and planktonic animals) occurred.

Economic Importance for Humans: Negative

No negative economic effects by the megamouth shark have been reported.

Conservation Status

Despite its vast size, this particular species of shark was only discovered in 1976. Less than ten have been studied or even sighted, and as a result, knowledge is limited.

Other Comments

Though its large size and huge mouth can create a sinister appearance, this shark is particularly timid.

Contributors

Melissa Kim (author), University of Michigan-Ann Arbor.

Glossary

Pacific Ocean

body of water between the southern ocean (above 60 degrees south latitude), Australia, Asia, and the western hemisphere. This is the world's largest ocean, covering about 28% of the world's surface.

World Map

benthic

Referring to an animal that lives on or near the bottom of a body of water. Also an aquatic biome consisting of the ocean bottom below the pelagic and coastal zones. Bottom habitats in the very deepest oceans (below 9000 m) are sometimes referred to as the abyssal zone. see also oceanic vent.

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

coastal

the nearshore aquatic habitats near a coast, or shoreline.

motile

having the capacity to move from one place to another.

natatorial

specialized for swimming

native range

the area in which the animal is naturally found, the region in which it is endemic.

References

Springer, Victor G., Gold, Joy P. 1989. Sharks in Question. Smithsonian Institute Press. Washington D.C. pp. 216-217

Stevens, J.D. 1987. Sharks. Facts on File Publications. New York. pg. 251

Wilson, Edward O. 1992. The Diversity of Life. W.W. Norton & Co. New York, London. pp. 118-119