Mola Alexandrini

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Mola Alexandrini
Mola alexandrini (Bump-head Mola) .jpg

Mola Alexandrini

Systematics
Spinefish (Acanthopterygii)
Perch relatives (Percomorphaceae)
Order : Puffer fish (Tetraodontiformes)
Family : Sunfish (Molidae)
Genre : Mola
Type : Mola Alexandrini
Scientific name
Mola Alexandrini
( Ranzani , 1839)

Mola alexandrini ( Syn .: Mola ramsayi , English Bumphead sunfish) is a rare and little known species of the sunfish (Molidae). The range of the species is only vaguely known. Catches are from the Mediterranean Sea, the coast of Japan, the southwest Pacific near Australia and New Zealand , the eastern Pacific, the northern Indian Ocean and the eastern Atlantic, but the species may be found in tropical and temperate seas around the world in front. She seems to need a little more warmth than Mola mola .

features

Mola alexandrini is very similar to the better-known sunfish species Mola mola and has a highly oval, laterally flattened body. The most noticeable differences are a forehead hump that extends from above the eye to the base of the dorsal fin, but is only seen in specimens that are longer than 160 cm, and a chin that is inflated from the lower jaw to below the pectoral fins, but only at one length more than 135 cm occurs. On the sides of the head there are two horizontal elevations that extend from above and below the eyes to behind the pectoral fins. They develop with age. The scales in the middle of the body are rectangular and smooth in Mola alexandrini , conical with a frayed tip in Mola mola and conical without a frayed tip in Mola tecta . The whole body, with the exception of the fins, is covered with an insulating, thick, white gelatinous layer. The mouth is terminal and small, the teeth have grown together and form a kind of beak. In the case of very large specimens, the snout, in fish the area from the front edge of the eyes to the tip of the head, may protrude a little further than the mouth. The eyes are small. There is a pair of nostrils in front of each eye. The small gill opening is just in front of the base of the pectoral fin. It is partially covered by a soft membrane. The gill rakes are hidden under a gelatinous layer. A lateral line organ is only present on the head.

The pectoral fins are small and round. They are located in the middle of the body and can be placed in shallow pits on the sides of the body. Ventral fins are missing. The dorsal and anal fins face each other symmetrically and serve as powerful main driving organs, they are short but high, triangular in shape, without fin rays and are supported by cartilage plates. The tips of the fins change from an acute angle to an obtuse angle with age. The clavus, the edge of the skin at the end of the body or the pigtail fin, is round, usually not wavy and without incision, as in Mola tecta . It is supported by 14 to 24 cartilage plates and specimens that are longer than 60 cm have 8 to 15 bones at the edge of the clavus. There is an additional bones on the muzzle and one on the chin. Females have a single, round ovary, while males have paired, rod-shaped testicles. External gender differences are not known.

The upper half of the body of Mola alexandrini and all fins are usually dark gray or dark red-brown, the lower half of the body is whitish. There are larger or smaller light spots distributed over the whole body. Mola alexandrini can change its coloring instantly. The largest known specimen of Mola alexandrini was caught off the coast of the Japanese prefecture of Miyagi on August 11, 2004 . It was 3.32 meters long.

Taxonomy

The species was first described in 1839 by Camillo Ranzani, then director of the Natural History Museum of Bologna, under the scientific name Orthragoriscus alexandrini , but later synonymous with Mola mola . However, a study published in 2017 revealed that the fish described as Orthragoriscus alexandrini and the fish described in 1883 by the Italian zoologist Enrico Hillyer Giglioli as Orthragoriscus ramsayi are the same species. The latter is a junior synonym of Orthragoriscus alexandrini and the name that is valid for the species today is Mola alexandrini .

literature

Web links

Commons : Mola alexandrini  - collection of images