Turtle/tortoise term 

Plastrum: The ventral (bottom) part of a turtle or tortoise shell.

Some plastrums are all one piece and very hard (like a galapagos tortoise, which needs a lot of support for its weight). Some are soft and pliable to allow the animal to squeeze into certain spaces (a notable example being pancake tortoises, which are born with a round shell that flattens with age, and their plastrum is very flexible and can be partially collapsed or inflated to protect it from being picked out of its hiding place by a predator). Some are hinged to allow the shell to close up (a notable example is a three-toed box turtle which is double hinged and can close its shell on both ends to keep it safe during predator attacks and allow it to neatly camouflage as a rock).

Plastrums are cool! :3

Sign in to participate in the conversation
Dragon Style

I'm a grumpy queer dragon lady and this is my quiet cave for me and some friends.