Fun Fact Friday: Myth About Mice

Do mice and rats have skeletons made of collapsible cartilage?  People assume that because rats and mice can fit through tiny spaces, they must have some special kind of collapsible skeleton with rubbery bones.  Nope.  They have your average every day skeleton.  So how do they do it?  I mean rats (smaller ones not giants) can fit through a hole the size of a quarter and mice can of course fit through even tinier places.

Well, the bottom line is, even though they are moving fast, they gauge whether or not they can fit through a hole before diving in.  And how do they do that?  Whiskers baby.  It's all about the whiskers.  So rodents will feel with their whiskers (by sticking their nose in a hole) before diving in, if they won't fit they quickly dash to another place, where they will fit.  If they do fit, they dive right in and disappear much to the discontentment and disgust of people everywhere.

So how do they actually fit?  Well, it's simple.  Rats and mice are kind of torpedo shaped and they are designed for digging burrows and moving through tunnels.  Considering that burrowing and tunneling is what they do, it makes sense that tiny holes and spaces are no issue for them.  So there you have it.  If you've been told about, or read about the magical all cartilage collapsible skeleton of rodents, it's a myth.  Like all vertebrates, they have skeletons made of bones, joints and cartilage- and it doesn't come apart or collapse to allow them to pass through small spaces.

What CAN they do?  Well, the truth is they can wiggle and squeeze their way into some pretty tiny spaces- and they can do it fast.  They are capable of expelling some air from their chest cavity to better fit in tiny spaces and they are smaller than they look (kind of like a person can suck in their stomach to fit into smaller jeans).  Even short fur makes rodents look a little bulkier than they actually are.  They use their skeletal structure to their advantage, but they do not have a special collapsible skeleton made entirely of cartilage.

In the wild, they have small tunnel entrances into their burrows to camouflage and keep their burrows hidden from predators.  Being able to quickly dash and dive into a tunnel, hole, small space is part of what they do naturally, whether they are in the wild or alongside people.