Galaxies

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Galaxies
Galaxias vulgaris

Galaxias vulgaris

Systematics
Subclass : Neuflosser (Neopterygii)
Subclass : Real bony fish (Teleostei)
Overcohort : Clupeocephala
Cohort : Euteleosteomorpha
Order : Galaxiiformes
Family : Galaxies
Scientific name of the  order
Galaxiiformes
Berg , 1940
Scientific name of the  family
Galaxiidae
Müller , 1844

Galaxies (Galaxiidae) are a family of small minnows - or trout-like freshwater fish , which in the temperate zone in the southern hemisphere are the ecological equivalent of the salmon fish (Salmonidae) in the northern hemisphere. In German they are also called Hechtlinge , a name that is also used for various egg-laying toothcarps that are not related to the Galaxiidae .

distribution

They live in cold fresh waters in Australia (approx. 25 species), Tasmania (15 species), New Zealand (22 species), Lord Howe Island , the Chatham Islands , the Auckland Islands and Campbell Island , in New Caledonia (1 species) , southernmost South Africa (1 species), southern South America (4 species) and the Falkland Islands . Galaxias maculatus inhabits a large part of the family's range. This was explained by the theory of continental drift . It has now been shown that populations from the western and eastern Pacific are genetically very similar and that the wide distribution of the species can be explained by the marine larval stage.

features

Galaxies are elongated, trout-like or minnow-like, scale-less fish that can be three to a maximum of 60 cm long. Her hull is without a honey keel, there is a sideline . The caudal fin has 12 to 14 branched main fin rays. The dorsal and anal fins face each other and are far behind the center of the body. The maxillary , ploughshare , palatine bone and basibranchial (bones at the base of the branchial arch) are edentulous. The gonads are created in pairs.

Way of life

Galaxies live in cool summer waters in the temperate zone of the southern hemisphere. They feed on aquatic insects and approach food (insects that fall into the water) and are good jumpers. Many species of galaxies (unlike the anadromous salmon fish) are catadromous migratory fish that migrate downstream to the estuary to lay eggs. The development of eggs and larvae takes place in the sea. The fry later migrate back into the freshwater. Many species are short-lived, some only have a one-year life cycle.

Phylogenetic position of the galaxies
  Euteleosteomorpha  

 Lepidogalaxii


   
  Protacanthopterygii  

 Golden salmon (Argentiniformes)


   

 Galaxies (Galaxiiformes)


   

 Pike-like (Esociformes)


   

 Salmonid fish  (Salmoniformes)





   
  Stomiati  

 Smelt-like
 (Osmeriformes)


   

 Maulstachler
 (Stomiiformes)



   

 Neoteleostei





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External system

The galaxies were previously placed in the order of the smelt-like (Osmeriformes) and formed the superfamily Galaxioidea with the New Zealand salmon (Retropinnidae) and Lepidogalaxias salamandroides (family Lepidogalaxiidae) . According to a more recent phylogenetic investigation, however, the family is outside of the smelt-like family and is the sister group of the pike-like (Esociformes) and the salmon-like (Salmoniformes), while the smelt-like (without Lepidogalaxias ) is the sister group of the deep-sea muzzle (Stomiiformes). In the latest revision of the bony fish systematics, the galaxies are therefore given a ranking (Galaxiiformes). Together with the golden salmon-like (Argentiniformes), the pike-like and the salmon-like, the Galaxiiformes form the sub-cohort Protacanthopterygii .

Internal system

There are two subfamilies, seven genera and about 65 species:

Subfamily Galaxiinae

The approximately 60 species from the subfamily Galaxiinae are scaly and have no adipose fin . They have 37 to 66 vertebrae.

Galaxias argenteus
Galaxias brevipinnis
Galaxias maculatus
Galaxias cf. olidus
Galaxias postvectis
Galaxias truttaceus
Aplochiton sp.

Subfamily Aplochitoninae

The four species of trout pike (subfamily Aplochitoninae) are 7.7 to 38 centimeters long, have no scales and have an adipose fin and 52 to 74 vertebrae.

Fossil record

Fossil galaxies of the genus Galaxias are known from New Zealand. May need Stompooria from the Late Cretaceous period are also provided by South Africa to the family.

literature

Individual evidence

  1. ↑ R. Betancur-R., E. Wiley, N. Bailly, A. Acero, M. Miya, G. Lecointre, G. Ortí: Phylogenetic Classification of Bony Fishes - Version 4 (2016)
  2. ↑ Ricardo Betancur-R, Edward O. Wiley, Gloria Arratia, Arturo Acero, Nicolas Bailly, Masaki Miya, Guillaume Lecointre and Guillermo Ortí: Phylogenetic classification of bony fishes . BMC Evolutionary Biology, BMC series - July 2017, DOI: 10.1186 / s12862-017-0958-3
  3. ↑ a b c d e f g h i j k l m Tarmo A. Raadik: Fifteen from one: a revision of the Galaxias olidus Günther, 1866 complex (Teleostei, Galaxiidae) in south-eastern Australia recognizes three previously described taxa and describes 12 new species. Zootaxa 3898 (1): 001–198 (Dec. 2014) doi: 10.11646 / zootaxa.3898.1.1

Web links

Commons : Galaxiidae  - Collection of images, videos and audio files