Northern pike

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Northern pike
Belonesox belizanus.jpg

Northern pike ( Belonesox belizanus )

Systematics
Order : Toothpies (Cyprinodontiformes)
Subordination : Cyprinodontoidei
Family : Viviparous toothcarps (Poeciliidae)
Subfamily : Live-bearing toothcarps (Poeciliinae)
Genre : Belonesox
Type : Northern pike
Scientific name of the  genus
Belonesox
Kner , 1860
Scientific name of the  species
Belonesox belizanus
Kner, 1860

The belonesox belizanus ( Belonesox belizanus ), also known as (livebearer) Hechtkopf , Hornhechtkärpfling and needle Hecht , is the largest species of live-bearing tooth carp (Poeciliinae). The only species of the thus monotypical genus Belonesox occurs east of the main watershed on the Caribbean side of Central America from southern Mexico to Nicaragua . The generic name is made up of belone ( Gr . For arrowhead) and esox ( Lat . For pike), the specific epithet was derived from Belize as part of the distribution area.

distribution

The distribution begins in the north with the Laguna San Julian north of Veracruz in Mexico and ranges over the peninsula of Yucatan to the border between Nicaragua and Costa Rica . Exposed by aquarists, he was able to establish himself in Florida , e.g. B. in the Everglades since 1957.

features

Pike fish reach average lengths between 10 cm (males) and 15 cm (females), older females can be a maximum of 20 cm long. They are elongated, slender fish whose body is slightly flattened on the sides and covered with numerous, very small scales. The body of the pike fish is brown, olive brown or gray-yellow in color and becomes blackish at night. The chest and stomach are dirty white. In incident light, the body shimmers bronze. Some longitudinal rows of dark spots may appear on the sides of the body. At the base of the caudal fin is a round, black, light-edged spot that often fades in females. The fins are colorless or yellowish and have a slightly dark edge. Young fish up to a length of 5 cm show a black-brown longitudinal band or an almost completely black color. An actual sideline is missing, the sensory channels are limited to the head.

The head is pointed, noticeably large and ends in an elongated, beak-like and deeply split mouth. The eyes are large, the pupil can be camouflaged by a black stripe. Both jaws are covered with several rows of pointed teeth, the teeth in the outer rows are shorter and get longer inward. In the wide upper jaw, which consists only of the triangular premaxillary , the widest point is occupied by 12 transverse teeth. The lower jaw is toothed on the edge in three rows, the midline is toothless here. Due to the convex curvature of the forceps-like jaw, the mouth cannot be completely closed - the teeth are always visible. The upper jaw is lower and slightly shorter than the lower jaw. The mouth is a bit overhead, but can be easily lowered when grabbing, as the prey has a tendency to flee downwards from the surface and the premaxillary advances somewhat. The mouth can be opened surprisingly wide. The pharyngealia resemble rigid "tooth-brushes". The throat is very elastic, the stomach a large sack. The four gill arches are covered on the inside with numerous, very small teeth ( gill trap ). The forehead is broad, so the head is flattened.

The dorsal fin starts far back. In addition to their small size, the males differ from the females by their gonopodium and the rays of the dorsal fin, which extend beyond the fin membrane . Sometimes the dorsal fin of the males is also darkly dotted.

Way of life

The pike fish, which need warmth, inhabit fresh and brackish waters and also tolerate polluted waters with a low oxygen content. They are predatory fish that live mainly in the upper water layers and feed almost exclusively on smaller fish. Pike larvae lie in wait for their prey and strike like a pike with lightning speed or they slowly stalk their prey using hiding places. Chases also occur. The gestation period is 30 to 50 days. A maximum of 100 young fish are born per litter between 20 and 80, which are 14 to 18, according to other information, 35 mm long at birth. The juvenile fish feed on small crustaceans such as water fleas for the first two to three weeks, after which they switch to the piscivorous diet of the adult animals.

Systematics

The pike pike belong to the Gambusini tribe within the viviparous toothcarps . Their closest relatives are the Gambusia ( Gambusia ) that probably the sister group of Belonesox form. Some scientists also take the view that the pike fish represents a predatory extreme of the gambus and must be assigned to this genus. Belonesox would become the junior synonym of Gambusia . A subspecies frequently mentioned in the literature B. b. maxillosus is controversial.

literature

  • H. Greven and M. Brenner: Further remarks on the dentition and prey capture of the pike fish Belonesox belizanus (Poeciliidae). Bulletin of Fish Biology, Volume 10, No. 1/2, 2008, pages 97-103 PDF online
  • Rudolf Kner : About Belonesox Belizanus, nov. gen. et spec. from the cyprinodont family. (Online at books.google.at)
  • Helmut Stallknecht : Live-bearing toothcarps . Neumann Verlag, 1989, ISBN 3-7402-0055-3 .
  • Günther Sterba (Ed.), Gert Brückner: Encyclopedia of Aquaristics and Special Ichthyology. Neumann-Neudamm, Melsungen u. a. 1978, ISBN 3-7888-0252-9 .
  • Günther Sterba: The world's freshwater fish. 2nd Edition. Urania, Leipzig / Jena / Berlin 1990, ISBN 3-332-00109-4 .
  • Dieter Gentzsch: Belonesox belizanus. In: Claus Schaefer, Torsten Schröer (Hrsg.): The large lexicon of aquaristics. Eugen Ulmer, Stuttgart 2004, ISBN 3-8001-7497-9 , pp. 144 f.

Individual evidence

  1. James Roy Kerfoot Jr., Ph.D .: The influence of temperature on the physiology and feeding behavior of the invasive pike killifish, Belonesox belizanus, in south Florida. (Abstract online )
  2. Paulo Henrique Franco Lucinda, Roberto E. Reis: Systematics of the subfamily Poeciliinae Bonaparte (Cyprinodontiformes: Poeciliidae), with an emphasis on the tribe Cnesterodontini Hubbs. Neotrope. ichthyol. vol. 3 no. 1 Porto Alegre Jan./Mar. 2005 doi : 10.1590 / S1679-62252005000100001

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