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These scales were easily dispersed after death; their small size and resilience makes them the most common vertebrate fossil of their time. [ 14 ] [ 15 ] The fish lived in both freshwater and marine environments, first appearing during the Ordovician , and perishing during the Frasnian–Famennian extinction event of the Late Devonian .
Apart from electric rays, which have a thick and flabby body, with soft, loose skin, chondrichthyans have tough skin covered with dermal teeth (again, Holocephali is an exception, as the teeth are lost in adults, only kept on the clasping organ seen on the caudal ventral surface of the male), also called placoid scales (or dermal denticles ...
However, their ancestors were bony animals, and were the first fish to develop paired fins. Cartilaginous fish don't have swim bladders. Their skin is covered in placoid scales (dermal denticles) that are as rough as sandpaper. Because cartilaginous fish do not have bone marrow, the spleen and special tissue around the gonads produces red blood ...
Sticklebacks are carnivorous, feeding on small animals such as insects, crustaceans and fish larvae. [8] [9] Sticklebacks are characterised by the presence of strong and clearly isolated spines in their dorsal fins. [10] An unusual feature of sticklebacks is that they have no scales, although some species have bony armour plates.
No scales are present, and the fins are very fragile. Lancetfishes are among the largest living bathypelagic fish forms. Specimens have been collected in excess of 2,080 mm (6.82 ft) in length, often from dead individuals that drifted ashore.
The 17th-century Turkish Sephardi halakhic authority Rabbi Chaim ben Yisrael Benvenisti wrote that "It is a widespread custom among all Jews to eat the fish with the sword, known in vernacular as fishei espada, even though it does not have any scales. Because it is said that when it comes out of the water, due to its anger, it shakes and throws ...
The skipjack tuna (Katsuwonus pelamis) is a perciform fish in the tuna family, Scombridae, and is the only member of the genus Katsuwonus. It is also known as katsuo, arctic bonito, mushmouth, oceanic bonito, striped tuna or victor fish. It grows up to 1 m (3 ft) in length. It is a cosmopolitan pelagic fish found in tropical and warm-temperate ...
Cosmoid scales have the same two layers of bone that ganoid scales have except they have dentin in-between the enamel and vascular bone and lamellar (vascular and lamellar two subcategories for bone found in scales). All these scales are found underneath the epidermis and do not break the epidermis of the fish. Unlike the placoid scales that ...