Types of Roly-Poly

The roly-poly is well known for its hard exoskeleton.

The prevalence of pill bugs, or roly-polies, in any moist area, including lawns, gardens and wooded areas, makes them one of the most identifiable creatures of their size. The roly-poly is scientifically categorized as an isopod, referring to its seven sets of legs acting in unison, the most common of which measure less than 1/4 inch extended and found primarily in areas that help them avoid exposure and predation.

Identifiers

Roly-polies are most identifiable by their size and their shell. The hard gray or brown exoskeleton of the roly-poly covers the eight-sectioned thorax. The front section of the thorax connects to the head, which has visible, albeit tiny, antenna, mouth and eyes. The rear seven sections of the thorax can roll into a ball for protection. In most cases, human interaction will cause this reaction from the bug. The roly-poly will then straighten out again when the threat appears to have gone.

Common Types

Roly-polies are closely related to the wood louse and the sow bug. All such isopods can be described as hidden animals because of their natural habitat beneath rocks or logs or in any place that appears to allow them to burrow. In order to grow to full size, all crustaceans, including pill bugs, undergo molting periods to expose a larger exoskeleton. Pill bugs can molt four to five times during their lifespans.

Marine Life

As a type of arthropod, roly-polies are members of the crustacean family and distant relatives of the crab, shrimp and lobster. Marine sow bugs have the same identifiers as common garden roly-polies, including seven sets of legs, an eight-section thorax and a head with a set of antenna. They grow to between 7 and 10 ten meters in length and weigh up to 3 pounds.

Predation and Disease

While pill bugs remain a common diet for many creatures, their exoskeleton provides good protection from predators that do not wish to fight their way through the hard shell. Roly-polys can become a garden nuisance purely by producing large, healthy populations, but they do not appear to be a threat to the growth of plants or vegetables.

References

• Enchanted Learning: Pill Bug: An Isopod
• Fossweb: Isopods
• Handbook of Biological Statistics: Types of Variables