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The dorsal fin spines of dogfish sharks and chimaeras, the stinging tail spines of stingrays, and the "saw" teeth of sawfishes and sawsharks are fused and modified placoid scales. Surgeonfish have a scalpel-like blade, which is a modified scale, on either side of the caudal peduncle. [56]
Placoid Scale. Super Smooth scales (dermal denticles) coat the skin of sharks, rays, and cartilaginous fishes due to the absence of dermal bone. These scales are present in the dermis, which has fibrous connective tissue components, and project through the epidermis, which contains secretory cells and stratified epidermal cells, to the surface.
Placoid scales are found on cartilaginous fish including sharks and stingrays. These scales, also called denticles, are similar in structure to teeth, and have one median spine and two lateral spines. The modern jawed fish ancestors, the jawless ostracoderms and later jawed placoderms, may have had scales with the properties of both placoid and ...
Sharks portal; Scoliodon is a genus of requiem sharks in the family Carcharhinidae. [1] It was formerly thought to include only a single Indo-Pacific species, the spadenose shark (S. laticaudus), but recent taxonomic research has found an additional species, the Pacific spadenose shark (S. macrorhynchos).
The Portuguese dogfish (Centroscymnus coelolepis) or Portuguese shark, is a species of sleeper shark of the family Somniosidae. This globally distributed species has been reported down to a depth of 3,675 m (12,057 ft), making it the deepest-living shark known. It inhabits lower continental slopes and abyssal plains, usually staying near the ...
Dogfish sharks use their strong jaw and sharp teeth to consume their prey. The spiny dogfish has broken several records in the areas of migration and gestation. This shark tends to be a highly migratory species: one shark was recorded as travelling 8,000 km (5,000 miles) after being tagged in Washington state, United States, and found again ...
The Pacific spiny dogfish (Squalus suckleyi) is a common species of the Squalidae (dogfish) family of sharks and are among the most abundant species of sharks in the world. This species is closely related to the Spiny dogfish and for many years they were treated as a single species. [ 4 ]
Protosqualus ("Primitive Squalus") was a genus of dogfish shark that existed during the Cretaceous. Fossils have been found in Europe (mainly in France, Russia, Germany, Lithuania, The United Kingdom and Ukraine), East Asia (mainly in Japan), [5] Antarctica, [6] Australia, [7] India and South America.