How is the inside surface area maximized in each animal dogfish shark?

The inside surface area is shaped in a crescent. It consists of a spiral valve which is made up of the small intestine. Although the dogfish shark has a relatively short small intestine compared to other animals, therefore, the spiral valve allows for a more compact form of the small intestine.
Hence, this structure provides maximum surface area over a relatively short distance in order to make the absorption of nutrients efficient achieved from the food, the sharks had from eating different sea animals.

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