Shore Buddies Wisdom Wednesday
Image by Instagram user @zackvibes
Sharks do not have bones! Their insides are instead made of cartilage similar to that of human noses and ears. Even though sharks don't have bones, they still can fossilize. As most sharks age, they deposit calcium salts in their skeletal cartilage to strengthen it. The dried jaws of a shark appear and feel heavy and solid; much like bone. These same minerals allow most shark skeletal systems to fossilize quite nicely. The teeth have enamel so they show up in the fossil record too. Sharks have such good eyesight, they can actually see in color! Shark skin feels exactly like sandpaper because it is made up of tiny teeth-like structures called placoid scales, also known as dermal denticles. These scales point towards the tail and help reduce friction from surrounding water when the shark swims. When you flip a shark upside down they go into a trance like state called tonic immobility. This state lets them slow their breathing and heart rate, since sharks have to keep swimming in order to pump water over their gills. Similar to determining the age of a tree, Scientists age sharks by counting the rings on their vertebrae. Vertebrae contain concentric pairs of opaque and translucent bands. Band pairs are counted like rings on a tree and then scientists assign an age to the shark based on the count.