Blog: Angioseal Procedure

Sharks have survived five major extinctions that wiped out the majority of life on earth during different stages of its history. So how have sharks survived and what life functions and morphology have they evolved to be so successful? What conservation exists and what are the anthropogenic threats to sharks?

Evolution and Anatomy of Sharks

The history of sharks stretches far back beyond the dinosaurs. Fossil records indicate that sharks evolved from the Ordovician period. Unlike many fish, sharks have a cartilaginous skeleton, built in an extremely stream lined design, which allows them to cut through the water to reach their prey rapidly. The absence of more solid material like bone is also a mechanism that allows the shark family to withstand the pressure found at depth.

Another difference between the shark family and bony fishes is the absence of a swim bladder. The swim bladder is a structure that helps maintain fish buoyancy at varying depths in the ocean, however this is not found in sharks. Instead, they have developed a large oil-based liver which enables buoyancy control. This lack of a swim bladder also means that when sharks are brought up from the depths by humans they are not as likely to get damaged as fish with swim bladders.

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