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A fish scale is a small rigid plate that grows out of the skin of a fish. The skin of most jawed fishes is covered with these protective scales, which can also provide effective camouflage through the use of reflection and colouration, as well as possible hydrodynamic advantages.
Thelodonti ('feeble-teeth') are a group of small, extinct jawless fishes with distinctive scales instead of large plates of armour. There is much debate over whether the group of Palaeozoic fish known as the Thelodonti (formerly coelolepids [ 11 ] ) represent a monophyletic grouping , or disparate stem groups to the major lines of jawless and ...
Osteichthyes (/ ˌ ɒ s t iː ˈ ɪ k θ iː z / ost-ee-IK-theez), [2] also known as osteichthyans or commonly referred to as the bony fish, is a diverse superclass of vertebrate animals that have endoskeletons primarily composed of bone tissue.
These fish are best kept with live or frozen feed and they easily outgrow the tank within eight to ten months. An aquarium with the minimum diameter of 6 by 3.5 feet (1.8 by 1.1 m) and 300 US gallons (1,100 L; 250 imp gal) is suggested as a bare minimum but 400–800 US gallons (1,500–3,000 L; 330–670 imp gal) is the best way to go. [ 9 ]
The bony fish lineage shows more derived anatomical traits, often with major evolutionary changes from the features of ancient fish. They have a bony skeleton, are generally laterally flattened, have five pairs of gills protected by an operculum, and a mouth at or near the tip of the snout. The dermis is covered with overlapping scales. Bony ...
Aristotle (ca. 340 B.C.) may have been the first scientist to speculate on the use of hard parts of fishes to determine age, stating in Historica Animalium that “the age of a scaly fish may be told by the size and hardness of its scales.” [4] However, it was not until the development of the microscope that more detailed studies were performed on the structure of scales. [5]
Armor-like scales coated with ganoin found in gars and bichirs. genital papilla A small, fleshy tube behind the anus in some fishes, from which the sperm or eggs are released; the sex of a fish often can be determined by the shape of its papilla. gill arches The bony arches to which the gills are attached. gill cover
Odontodes typically cover the body of chondrichthyans (cartilaginous fishes), while mineralized dermal scales are characteristic of bony fishes. During the evolution to bony fishes, ancestral odontodes have been modified to become dermal scales, including elasmoid scales in teleosteans. [4]