Skeletal/Muscular system
A shark’s skeleton is composed of cartilage, this is a flexible structure that grows with the shark and is lighter than bone. It is composed of specialized cells called chondrocytes that produce an extracellular matrix of collagen fibers, proteoglycan and elastin fibers.
Bone is essentially cartilage that has been hardened by mineral calcification, during which calcium crystals provide extra hardness and rigidity. Calcification does occur in parts of the shark including its vertebrae, teeth, parts of the jaw, fin rods and denticles
Sharks have 3 main muscle classes
1. Cardiac muscle in the heart which works continuously
2. Visceral muscles / smooth muscles are found in various internal parts such as the guts, arteries, excretory and reproductive organs. Contraction of these muscles allows passage of contents through these parts
3. Skeletal muscles that move the skeleton are made up of 2 types:
-Red muscle present in thin layers underneath the shark’s skin, this works by breaking down fats in the shark’s body. It has a good blood supply and allows the shark to swim slowly for long periods without tiring
-White muscle works by using the energy from the breakdown of sugars, it has a poor blood supply and is used only for short fast bursts of swimming when chasing prey or avoiding danger
Bone is essentially cartilage that has been hardened by mineral calcification, during which calcium crystals provide extra hardness and rigidity. Calcification does occur in parts of the shark including its vertebrae, teeth, parts of the jaw, fin rods and denticles
Sharks have 3 main muscle classes
1. Cardiac muscle in the heart which works continuously
2. Visceral muscles / smooth muscles are found in various internal parts such as the guts, arteries, excretory and reproductive organs. Contraction of these muscles allows passage of contents through these parts
3. Skeletal muscles that move the skeleton are made up of 2 types:
-Red muscle present in thin layers underneath the shark’s skin, this works by breaking down fats in the shark’s body. It has a good blood supply and allows the shark to swim slowly for long periods without tiring
-White muscle works by using the energy from the breakdown of sugars, it has a poor blood supply and is used only for short fast bursts of swimming when chasing prey or avoiding danger