If someone asked you what your skeleton was made of, you wouldn’t take long to answer “bones!” Our skeleton, which is made of many bones fitted together, helps support our bodies and let us move around. But there are a few animals who have a complete skeleton without having a single bone in their bodies!
If someone asked you what your skeleton was made of, you wouldn’t take long to answer “bones!” Our skeleton, which is made of many bones fitted together, helps support our bodies and let us move around. But there are a few animals who have a complete skeleton without having a single bone in their bodies!
Try this: take the tip of your ear between your fingers and wiggle it around gently. Can you feel how your ear has its own shape, but is also flexible? That’s because your ear (along with your nose and parts of the joints in your body) is made out of something called cartilage.
We only have a little cartilage in our bodies, but there is a family of fish, which includes sharks and stingrays, whose entire skeletons are made out of cartilage!
By having skeletons made of cartilage instead of bone, sharks and rays may lose some strength (they’d never be able to move around out of the water), but in exchange, they gain incredible flexibility. This helps sharks reach terrifying speeds when they’re hunting, and allow stingrays to accomplish the graceful “flying” motion of their wings when they’re moving through the water.
Even the teeth of sharks and stingrays aren’t made of bone. They’re actually very specialized scales! If you look closely at the skin of a shark under a microscope, the scales in its skin look like tiny versions of its teeth. That’s why a shark has very rough skin; some people even use it as sandpaper!
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