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| Shark skin feels
like sandpaper because it has small rough placoid scales (also known as dermal
denticles). As a result, it is often dried and used as a
leather product or sandpaper. Placoid scales consist of a basal bony plate buried within the skin and a raised portion that is
exposed. Dermal denticles are homologous in structure to teeth, and
are what gives the skin a rough feeling. |
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Dermal denticles, as seen in this image taken from the
dorsal fin of a porbeagle shark, are small tooth-like structures on the
skin which form a protective barrier and aid in swimming. |
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Magnified images of porbeagle and spiny dogfish dermal denticles taken by
scanning electron microscope. Images courtesy of Frank Thomas, MicroAnalysis Facility, GSC
Atlantic..
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porbeagle denticles (200X) |
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spiny dogfish denticles (180X)
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