2.1.2 The structure
A shark fin has very little muscle tissue. There is a membrane, and in some cases a fatty layer under the skin, covering a bundle of collagen fibres spread out like a fan. In most fins these fibres are supported by a cartilaginous platelet in the centre. The cartilaginous platelet is absent in the caudal fin.
Sharks do not have scales. The skin of the fins, like that of the rest of the shark’s body, is covered with large numbers of usually very small thorn-like structures or denticles. These make sharkskin feel like sandpaper.
The collagen fibres of the fin are rounded at the base, tapering to fine points at their extremities, giving the appearance of needles. Appropriately, they are commonly known as fin needles. Separately or joined as a bundle, the fin needles will eventually find their way in different preparations onto the dining table