Basking mouth shark

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Basking mouth shark
Basking mouth shark (Megachasma pelagios) in Toba Aquarium, Japan

Basking mouth shark ( Megachasma pelagios ) in Toba Aquarium, Japan

Systematics
without rank: Sharks (selachii)
Superordinate : Galeomorphii
Order : Mackerel shark (Lamniformes)
Family : Basking mouth sharks
Genre : Basking mouth sharks
Type : Basking mouth shark
Scientific name of the  family
Megachasmidae
Taylor , Compagno & Struhsaker , 1983
Scientific name of the  genus
Megachasma
Taylor, Compagno & Struhsaker, 1983
Scientific name of the  species
Megachasma pelagios
Taylor, Compagno & Struhsaker, 1983

The basking mouth shark ( Megachasma pelagios ) is next to whale shark and basking shark one of the three currently known shark species that feed on microorganisms. Since its discovery in 1976, he is the only way in which only one genus existing family of Megamouth sharks.

Since fewer than 25 specimens were sighted up to November 2004 and only a few of them have been scientifically investigated to date, little is known about the biology, habitat and behavior of these fish. The longest specimen measured so far was a 5.63 m long female that was washed ashore on April 19, 2004 near Ichihara in Tokyo Bay , the smallest was a 1.77 m male captured on March 13, 2004 in Sumatra Length.

The previous sightings in the Atlantic , Pacific and Eastern Indian Oceans , most of which took place off California and around the Japanese islands , suggest that basking mouth shark is a global inhabitant of the warmer oceans.

features

Head and mouth of a preserved basking mouth shark

Its most noticeable feature, which gives the basking mouth shark its name, is its relatively large, rounded head with its very short snout and large mouth. The color of the back is a blackish brown, the belly is pale. The basking mouth shark has two dorsal fins and an asymmetrical caudal fin.

Distribution, Behavior, and Diet

Probable distribution

The sightings and catches described suggest a worldwide distribution, even if no specimen was seen in the western Indian Ocean until 2004 and only individual specimens have been recorded in the Atlantic from the Senegalese , Brazilian and South African coasts.

The sightings of adult males ready to mate off the coast of California in October 1990, 1999 and 2001 suggest that basking mouth sharks mate there in autumn.

Examination of the stomach contents of dead animals revealed that the basking mouth shark's main diet consists of krill . Unlike the basking shark , which only passively filters the water containing plankton, the basking mouth shark (like the whale shark ) can actively suck in and filter water. It is not known whether smaller fish are also on his menu.

When, on October 21, 1990, a male almost five meters long got caught in a drift net in front of Dana Point, California , it was possible for the first time to photograph and film a living specimen and to release it with transmitters. During this telemetric investigation, knowledge about the vertical daily migration behavior of the shark in the water column of the ocean could be obtained. This animal spent the night at a depth of around 15 meters and the day at a depth of around 150 meters. It was assumed that the fish followed its main food krill, which also changes the water layers in this rhythm.

discovery

It is uncertain to what extent the basking mouth shark is responsible for narratives of sea monsters described as a mixture of whale and shark. The first secured catch of a basking mouth shark that led to the description of the species was on November 15, 1976 off Oʻahu , Hawaii , where the crew of a US research vessel brought a male 4.46 m long on board, which was bitten by a towline would have. The animal has been thoroughly examined and is now in the Bernice P. Bishop Museum in Honolulu .

literature

  • Leighton R. Taylor, Leonard J. Compagno, Paul J. Struhsaker: Megamouth. A new species, genus, and family of lamnoid shark (Megachasma pelagios, family Megachasmidae) from the Hawaiian Islands. In: Proceedings of the Californian Academy of Science , Vol. 43, No. 8, 1983, ISSN  0068-547X , pp. 87-110.

Web links

Commons : Basking mouth shark ( Megachasma pelagios )  - Collection of images, videos and audio files