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3D Models of Fish such as goldfish cod angel trout walleye roach northern pike perch and other such as whale horseshoe crab.
Fish are the paraphyletic group of aquatic vertebrates. An extensive group of jaw-necks, which are characterized by gill breathing at all stages of the postembryonic development of the organism. They live in both saline and freshwater bodies, from deep ocean depressions to mountain streams. These species play an important role in most aquatic ecosystems as part of the food chain. Many species are consumed by humans and therefore have an important commercial value.
The size of modern fish varies from 7.9 mm to 20 m (whale shark).
In the world known. About 300–500 species new to science are described each year. About 3,000 species inhabit Russia, including more than 280 species found in freshwaters.
It was believed that the most ancient jawless animals resembling fish are known from the early Ordovician (about 450-470 million years ago). However, in 1999, in the Chinese province of Yunnan, the fossils of the Haikouichthys fish-like creature from a jawless group of about 530 million years old (early Cambrian) were found. Perhaps these forms were the ancestors of all vertebrates.
The jaw, a derivative of one of the gill arches, became the difference between the first and the maxillary fish. In addition to the jaws, they have paired fins, an inner ear with three semicircular canals, and gill arches. Despite the appearance of the first maxillary fishes in the Ordovician, they occupied a subordinate position up to the Devonian. Thus, such species existed for more than 100 million years in the conditions of the prevalence of jawless, in contrast to the present time. Cartilaginous fish appeared at the turn of the Silurian and Devonian, about 420 million years ago, and reached their prime in the Carboniferous. Bastard fishes live in the world’s oceans from at least Devonian; it is possible that they already existed in the Silurian.