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Unlike bony fish, the sharks have a complex dermal corset made of flexible collagenous fibers and arranged as a helical network surrounding their body. [22] This works as an outer skeleton, providing attachment for their swimming muscles and thus saving energy. A similar arrangement of collagen fibers has been discovered in dolphins and squid ...
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]
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. [51] Their liver constitutes up to 30% of their total body mass. [35]
Cartilaginous fish (sharks and rays) have a more advanced immune system. They have three specialized organs that are unique to chondrichthyes; the epigonal organs (lymphoid tissues similar to mammalian bone) that surround the gonads, the Leydig's organ within the walls of their esophagus, and a spiral valve in their intestine. These organs ...
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 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]
Lampreys and sharks only possess a cartilaginous endocranium, with both the upper jaw and the lower jaws being separate elements. Bony fishes have additional dermal bone, forming a more or less coherent skull roof in lungfish and holost fish. The lower jaw defines the chin.
Acanthodians did, in fact, have a cartilaginous skeleton, but their fins had a wide, bony base and were reinforced on their anterior margin with a dentine spine. They are distinguished in two respects: they were the earliest known jawed vertebrates , and they had stout spines supporting their fins , fixed in place and non-movable (like a shark ...