The layer of dermal denticles creates a rough surface that is sometimes compared to sandpaper. Untanned shark skin, called shagreen , is used to sand and polish furniture. Having an internal body temperature that is dependent on the surrounding temperature. Most fishes, amphibians, and reptiles are ectothermic. Gill slits These are the slit-like openings behind a shark's head.
Most sharks have five pairs of gill slits, but some have six or seven pairs.
As a shark breathes, oxygen-rich water enters its mouth. The now oxygen-depleted water exits through the gill slits. Ichthyologist A scientist who studies fishes. Kelp forests Kelp forests are formed by giant kelp that grow off the coast of California. The kelp forests provide food and shelter to a wide variety of marine animals, including sharks.