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The shark kidney excretes urea that is needed for the shark to have in its system so the shark does not become dehydrated from living in seawater. [14] Sharks hearts have two chambers. The shark heart's main importance is providing oxygenated blood to the entire body while filtering out the deoxygenated blood. [15]
Unlike bony fish, sharks do not have gas-filled swim bladders for buoyancy. Instead, sharks rely on a large liver filled with oil that contains squalene, and their cartilage, which is about half the normal density of bone. [33] Their liver constitutes up to 30% of their total body mass. [39]
Sharks have keen olfactory senses, located in the short duct (which is not fused, unlike bony fish) between the anterior and posterior nasal openings, with some species able to detect as little as one part per million of blood in seawater. [61] Sharks have the ability to determine the direction of a given scent based on the timing of scent ...
The following outline is provided as an overview of and topical guide to sharks: Sharks (superorder Selachimorpha) are a type of fish with a full cartilaginous skeleton and a highly streamlined body. The earliest known sharks date from more than 440 million years ago, before the time of the dinosaurs. [1]
The entire body of a shark is a very efficient eating machine. Each organ has been fine-tuned for hunting and acquiring food. Sharks are built to feed: Here's why they are the ultimate eating machines
The shark's blood pressure falls by half as the blood vessels dilate to deliver more blood to the brain and heart. Unlike in bony fishes and tetrapods, the blood flow rate remains constant and there is no elevation of blood glucose levels. [18] The brains of sharks only consume a third as much ATP as those of teleosts. [16]
Cartilaginous fish, such as sharks and rays, have jaws and skeletons made of cartilage rather than bone. Megalodon is an extinct species of shark that lived about 28 to 1.5 Ma. It looked much like a stocky version of the great white shark , but was much larger with fossil lengths reaching 20.3 metres (67 ft). [ 10 ]
The shared trait of breathing via gills in bony fish and cartilaginous fish is a famous example of symplesiomorphy. Bony fish are more closely related to terrestrial vertebrates, which evolved out of a clade of bony fishes that breathe through their skin or lungs, than they are to the sharks, rays, and the other cartilaginous fish. Their kind ...