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Today on Animal Fact Files, we’re talking about roly polies. Roll your cursor over the sub button to stay up to date on new episodes! Thanks to Kasey for today’s suggestion! Apparently these critters have many common names; I’ve always known them as roly polies, so that’s what we’re going with today, but let us know in the comments what you call them! Roly polies look similar to sowbugs, but they’re different in that many roly poly species are able to roll up into a ball - a trick that has earned them the common name we’re going by on this episode! This rolling behavior is dual purposed in that it is defensive and it helps retain moisture. If you’ve ever wondered why a roly poly looks like the giant isopods living at the bottom of the ocean, you likely won’t be surprised to learn that roly polies are themselves also isopods. Of course, they’re obviously not giant sized like their ocean dwelling cousins. Roly polies actually moved from water onto land, and they’ve adapted to live a fully terrestrial life, but they still have some holdovers from their once watery lifestyle. Gills in an aquatic animal make sense, but in a fully terrestrial animal they’re somewhat out of place. Because of their gills, roly polies require moisture in order to live, and they’ll actually dry out and suffocate if they can’t get enough water. Take about a fish out of water… or… an isopod out of water… Roly polies are some of the only crustaceans that have developed an entirely terrestrial lifestyle.

After moving to land, roly polies set out to conquer the world, though it took them some time. Roly polies are originally from Europe, but at this point they’ve become what’s called a cosmopolitan species, meaning you can find them just about anywhere that’s suitable for them to live. As long as there’s enough water, and the temperature is appropriate, roly polies can be found just about anywhere. Of course, there can’t be too much water because they’ll drown in aquatic environments... Roly polies are generally nocturnal spending their days hiding under rocks or rotting logs. Rotting logs are a great place for roly polies because they offer a banquet of food. Roly polies almost exclusively eat decaying plant material. Like the earthworms we’ve discussed previously, these terrestrial crustaceans help to promote the development of topsoil. It has even been suggested that roly polies help reduce heavy metal ions in soil and may even contribute to regulating the global temperature by consuming fungus that releasing carbon dioxide into the atmosphere. So, even though some people see them as pests, they can actually be beneficial!

Roly polies live an average of two years but some can live longer. Babies will develop in a brood pouch carried by the female roly poly and hatch within a month’s time. The babies will stick around until their first molt, then head off on their own. During the course of a year a female may produce two or even three brood pouches all containing anywhere from 100 to 200 eggs. Throughout their lifetime, roly polies have to watch out for spiders, lizards, and small mammals who may take them for a tasty snack. Even some humans have partaken in meals of roly polies calling them wood shrimp. I don’t even eat regular shrimp, so I sure wouldn’t be trying one of these guys; how do you all feel about dining on roly polies?

For more facts on roly polies, check out the links in the description. Give a thumbs up for roly polies, and thank you for watching Animal Fact Files!