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Fishes are a paraphyletic group and for this reason, the class Pisces seen in older reference works is no longer used in formal taxonomy.Traditional classification divides fish into three extant classes (Agnatha, Chondrichthyes, and Osteichthyes), and with extinct forms sometimes classified within those groups, sometimes as their own classes: [1]
There are seven main taxonomic ranks: kingdom, phylum or division, class, order, family, genus, and species. In addition, domain (proposed by Carl Woese ) is now widely used as a fundamental rank, although it is not mentioned in any of the nomenclature codes, and is a synonym for dominion ( Latin : dominium ), introduced by Moore in 1974.
Win a tournament to collect the Quiz Winner userbox! Welcome to the Fish Quiz! This is a friendly quiz competition designed to test your general knowledge of fish. Any registered Wikipedians may answer this quiz's questions, but, only if you get them right may you post another one. Think of this quiz as a fun, interactive version of "Did you ...
The term phylum was coined in 1866 by Ernst Haeckel from the Greek phylon (φῦλον, "race, stock"), related to phyle (φυλή, "tribe, clan"). [4] [5] Haeckel noted that species constantly evolved into new species that seemed to retain few consistent features among themselves and therefore few features that distinguished them as a group ("a self-contained unity"): "perhaps such a real and ...
Siphonophorae (A) Rhizophysa eysenhardtii scale bar = 1 cm, (B) Bathyphysa conifera 2 cm, (C) Hippopodius hippopus 5 mm, (D) Kephyes hiulcus 2 mm (E) Desmophyes haematogaster 5 mm (F) Sphaeronectes christiansonae 2 mm, (G) Praya dubia 40 m (130 ft), (H) Apolemia sp. 1 cm, (I) Lychnagalma utricularia 1 cm, (J) Nanomia sp. 1 cm, (K) Physophora hydrostatica 5 mm
In practice, fish anatomy and fish physiology complement each other, the former dealing with the structure of a fish, its organs or component parts and how they are put together, such as might be observed on the dissecting table or under the microscope, and the latter dealing with how those components function together in living fish. The ...
Brachiopods (/ ˈ b r æ k i oʊ ˌ p ɒ d /), phylum Brachiopoda, are a phylum of animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, while the front can be opened for feeding or closed for protection.
Chondrichthyes (/ k ɒ n ˈ d r ɪ k θ i iː z /; from Ancient Greek χόνδρος (khóndros) 'cartilage' and ἰχθύς (ikhthús) 'fish') is a class of jawed fish that contains the cartilaginous fish or chondrichthyans, which all have skeletons primarily composed of cartilage.