They have many names: Pill-bug, roly-poly, potato bug, sow-bug and even wood lice. But what are they? These creatures are isopods. Iso means same or equal and pod means foot. Isopods have 14 legs that all look and function the same way. This distinguishes them from their crustacean cousins (like shrimp and crayfish!) that have legs that are modified to perform different functions, such as walking, feeding, feeling and grasping.
Like all crustaceans, isopods have a segmented outer shell (seven overlapping plates) that provides a measure of protection from the environment and predators. Here's another way they are like their aquatic relatives - rather than getting the oxygen they need to survive through lungs like most terrestrial organisms, isopods have gill-like structures located at the bases of their legs. That is why isopods must keep moist at all times—if they dry, they die.
If you are out looking for them try checking out areas near concrete - they need some grit to aid their digestion! We will be studying these small critters soon in our late fall classes of Lil Nature Kids and Lil Nature Families. We will be using one of our favorite books:
I'm a Pill Bug by Yukihisa Tokuda.