Fish

Fish ( Pisces) ( from Latin piscis "fish") are aquatic vertebrates that breathe with gills. In zoological nomenclature, the fish do not form a natural unit ( Monophylon ), so they are no kin group, but a group of morphologically similar animals. The doctrine of the biology of the fish is the Ichthyology (from Greek ἰχθύς ik t ʰ ʰ YS, fish).

Systematic groups of fish

• Cartilaginous fishes ( Chondrichthyes ) with the living almost exclusively in the sea sharks, rays and chimaeras;
• Bonefish in the broader sense ( Osteichthyes ), composed of Fleischflossern and Strahlenflossern. The flesh -finned fishes include the marine coelacanth and living in the southern hemisphere freshwater lungfish. The ray-finned fish close all other groups with, including all European freshwater fish.

• Other belonging to the pine Fischtaxa mouths, but they are only fossil- handed and extinct since the Palaeozoic, are represented by the placoderms and dogfish sharks ( Acanthodii ).

• Finally, sometimes the hagfish and lampreys ( as well as various extinct groups) to the " fish " are counted, who are living fish similar but jawless vertebrate groups in the sea and in fresh water.

Since fish represent in terms of cladistics therefore not monophyletic ( product derived from a common ancestry ) taxon, they are often written in the zoological systematics with quotation marks (" fish ", " Pisces" ) in order to identify it as so -called paraphyletic taxon.

Anatomy, physiology and reproductive biology

For this purpose, ( Osteichthyes ) can be found in the article bonefish detailed information.

Evolution and Biodiversity

The oldest known jawless fish -like (eg, the Pteraspidomorphi ) date from the early Ordovician to around 450-470 million years ago. The cartilaginous fishes appear from the border Silurian / Devonian in front of about 420 million years ago. Bony fish there in the sea since the Devonian, they began their development but possibly already in the Silurian.

Just over half of all living vertebrate species, namely currently around 32,500 species listed in FishBase (April 2013), belong to the " fish ". The number of recognized (so-called " valid " ) species changes on the one hand due to the many new discoveries, on the other hand, due to ongoing taxonomic revisions of individual groups of fish.

Economic importance and vulnerability

Significant in economic terms is the fishing of edible fish, but also the ornamental fish trade. Both, however, can threaten fish stocks. Pollution, river engineering, heating, exposing alien species and desiccation are other hazards for the fish.

On the ecological threat to fish, especially in Germany the regular proclamation as a fish of the year depending on a type intended to draw attention. In Austria and Switzerland, similar events will take place: Fish of the Year ( Austria ) and fish of the year ( Switzerland ).

Ecotoxicological significance

Fish are in water quality (oxygen concentration, pH, temperature, dissolved natural and anthropogenic substances) over their gills exposed to very direct and respond rapidly and sensitively to contaminants. They therefore serve as a common test and monitoring species and scientific model organism in ecotoxicology.

Cultural Significance

The fish used in Christianity as a symbol of recognition and drawing.

In heraldry, the fish is a common heraldic animal.

In China, the fish was a symbol of wealth due to a phonetic similarity.