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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.
The fish can live without hemoglobin via low metabolic rates and the high solubility of oxygen in water at the low temperatures of their environment (the solubility of a gas tends to increase as temperature decreases). [2] However, the oxygen-carrying capacity of icefish blood is less than 10% that of their relatives with hemoglobin. [16]
Polypterids are elongated fish with a unique series of dorsal finlets which vary in number from seven to 18, instead of a single dorsal fin.Each of the dorsal finlets has bifid (double-edged) tips, and are the only fins with spines; the rest of the fins are composed of soft rays.
[37]: p. 219 In freshwater fish the bladder is a key site of absorption for many major ions [38] in marine fish urine is held in the bladder for extended periods to maximise water absorption. [38] The urinary bladders of fish and tetrapods are thought to be analogous while the former's swim-bladders and latter's lungs are considered homologous.
This is a list of various species of marine invertebrates, animals without a backbone, that are commonly found in aquariums kept by hobby aquarists.Some species are intentionally collected for their desirable aesthetic characteristics.
Bony fish can be further divided into those with lobe fins and those with ray fins. Lobe fins have the form of fleshy lobes supported by bony stalks which extend from the body. [16] Lobe fins evolved into the legs of the first tetrapod land vertebrates, so by extension an early ancestor of humans was a lobe-finned fish.
Among vertebrates, jawless armoured fish (ostracoderms) declined in diversity, while the jawed fish (gnathostomes) simultaneously increased in both the sea and fresh water. Armoured placoderms were numerous during the lower stages of the Devonian Period but became extinct in the Late Devonian, perhaps because of competition for food against the ...
Chauliodus species are recognized by their large, fang-like teeth. They are so long that they would pierce the brain of the fish if misaligned. [3]One species of viperfish, C. sloani, have a sampled standard length of 64.0 to 260.0 mm, with a mean SL of 120.3mm.