The Cape sea urchin’s mouth is centred on the lower side of the body and is surrounded by a whorl of gills. A complex jaw and tooth apparatus in the mouth, known as Aristotle’s lantern, is used to fragment marine algae covering the rocks below the low tide zone or in rock pools.
Under the Magnifying Glass
Shark skin “tiny skin teeth”
Even though denticles are similar to scales, they are really modified teeth and are covered with a hard enamel.
Like our teeth, they have an inner core of pulp made up of connective tissues, blood vessels, and nerves, which is covered by a layer of dentine a hard calcareous material. This is finally covered by enamel-like vitrodentine, which provides a hard outer casing.
Dermal denticles protects Sharks and Rays skin from damage and parasites in addition to improving their fluid dynamics.