Round-scale marlin

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Round-scale marlin
Systematics
Carangaria
Order : Carangiformes
Superfamily : Swordfish relatives (Xiphioidea)
Family : Spearfish (Istiophoridae)
Genre : Tetrapturus
Type : Round-scale marlin
Scientific name
Tetrapturus georgii
Lowe , 1841

The round-scale spearfish ( Tetrapturus georgii ) is a poorly researched representative of the spearfish (Istiophoridae). Its exact range is unknown. It is certain that it was only determined from catches in Madeira , Sicily , the Strait of Gibraltar and the neighboring Atlantic off the coast of southern Portugal . It probably inhabits a large area in the eastern and central North Atlantic between 45 ° N and 20 ° N.

features

The round-scale marlin 'resembles the white marlin ( Kajikia albida ) in its external appearance, grows to a maximum of 1.84 meters in length, but usually remains 1.5 meters or less in length. The maximum published weight is 23.5 kg. The body is elongated, flattened on the sides and covered on the sides with rounded scales at the back. The scales on the back and belly are elongated and lie on top of each other like roof tiles. The rostrum forms a slender, long "spear" with a round cross-section. Both jaws and the palate are not covered with teeth. Gill trap rays are absent. Right and left Branchiostegal membranes have grown together completely.

The first of the two dorsal fins is very long and has a high, rounded tip that is higher than the body height of the fish. The anal fin is also raised in front. The second dorsal fin is small and short and is symmetrical to the second anal fin. The pectoral fins are long and extend beyond the curve of the sideline. The pelvic fins are placed on the sides when swimming quickly. Tetrapturus georgii has a single sideline . It runs in a curve above the pectoral fin base and then straight to the caudal fin base. The tail fin stalk has two strong keels on each side.

The anus is well in front of the beginning of the first anal fin, the distance between anus and anal fin is between the height of the anal fin and half of this height. The number of vertebrae is 24, of which 12 are trunk and 12 tail vertebrae. In contrast to other spearfishes, Tetrapturus georgii has an unspotted body and an unspotted first dorsal fin.

Way of life

The way of life, biology and reproduction of Tetrapturus georgii are unknown. They probably resemble that of other marlins. Eggs and larvae are not yet known either.

Systematics

The round-scale marlin is very similar to the white marlin, e.g. B. in its high neck and the high, broadly rounded front part of the dorsal and anal fin. It was discussed whether the known Tetrapturus georgii specimens could be hybrids between different marlin species. The assumption was rejected again. Further research must reveal whether Tetrapturus georgii is a valid species.

literature

  • Izumi Nakamura: FAO Species Catalog An Annotated and Illustrated Catalog of Marlins, Sailfishes, Spearfishes and Swordfishes Known to date. ISBN 92-5-102232-1 online

Web links