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Dorsal fin diagram with landmarks labeled. Fins allow the sharks to be able to guide and lift themselves. Most sharks have eight fins: a pair of pectoral fins, a pair of pelvic fins, two dorsal fins, an anal fin, and a caudal fin. Pectoral fins are stiff, which enables downward movement, lift, and guidance.
Simplified diagram of shark net. Drum lines; Shark net – submerged net placed around beaches to reduce shark attacks on swimmers; Shark proof cage – cage from which a SCUBA diver can examine sharks more safely; Shark repellent – method of driving sharks from an area, object, person, or animal
Any fossils, including fossil shark teeth, are preserved in sedimentary rocks after falling from their mouth. [13] The sediment that the teeth were found in is used to help determine the age of the shark tooth due to the fossilization process. [15] Shark teeth are most commonly found between the Upper Cretaceous and Tertiary periods. [16]
The shark traps the plankton in these filaments and swallows from time to time in huge mouthfuls. Teeth in these species are comparatively small because they are not needed for feeding. [97] Other highly specialized feeders include cookiecutter sharks, which feed on flesh sliced out of other larger fish and marine mammals. Cookiecutter teeth ...
The cookiecutter shark regularly replaces its teeth like other sharks, but sheds its lower teeth in entire rows rather than one at a time. A cookiecutter shark has been calculated to have shed 15 sets of lower teeth, totaling 435–465 teeth, from when it was 14 cm (5.5 in) long to when it reached 50 cm (20 in), [ 11 ] a significant investment ...
The teeth of Strigilodus tollesonae were “spoon-like,” which is considered ideal for crushing, McClatchy News reported. Teeth embedded in cave walls reveal new species of ancient sea creature ...
The bluntnose sixgill is a species of sixgill sharks, of genus Hexanchus, a genus that also consists of two other species: the bigeye sixgill shark (Hexanchus nakamurai) and the Atlantic sixgill shark (Hexanchus vitulus). Through their base pairs of mitochondrial genes COI and ND2, these three species of sixgills widely differ from one another.
Squalicorax, commonly known as the crow shark, is a genus of extinct lamniform shark known to have lived during the Cretaceous period. The genus had a global distribution in the Late Cretaceous epoch. Multiple species within this genus are considered to be wastebasket taxon due to morphological similarities in the teeth.