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Kids' Inquiry of Diverse Species


What do they look like?

These animals are somewhat flattened, and several times longer than wide. The top and sides of animals in this group are covered by a row of tough plates. Underneath they have 7 pairs of legs. On the head is a pair of antennae. Some species can curl up into a ball for protection, this is where they get the name "pillbug."

  • Sexual Dimorphism
  • sexes alike

Where do they live?

This is a group of over 3,800 species that are found all over the world. Most species of Isopods are marine, but this group evolved to live on land.

What kind of habitat do they need?

Pillbugs live just about anywhere there is moisture and dead plants to eat, but they are most common in forests and other humid habitats. A few live along the seashore, close to their marine relatives. They need humid conditions to survive.

How do they grow?

Like all arthropods, sowbugs have to shed their exoskeleton to grow. Once these little animals leave their mother's pouch (see below), they don't change shape or structure much, they just get bigger.

How long do they live?

  • Typical lifespan
    Status: wild
    2.0 to 3.0 years

How do they behave?

These animals don't move around too much. They avoid light and dryness. They aren't particularly social, but some are apparently attracted to the smell of their own kind.

How do they communicate with each other?

These animals have poor vision, and probably communicate chemically.

What do they eat?

Pillbugs graze on algae, fungus, moss, bark, and all kinds of decaying plant and animal material.

What eats them and how do they avoid being eaten?

Sowbugs and pillbugs roll up to protect themselves, they also have glands that make defensive chemicals. Their nocturnal habit probably helps them avoid some predators too.

What roles do they have in the ecosystem?

These animals are part of the community of species that break down dead plants and animals.

Species (or larger taxonomic groups) that are mutualists with this species
  • Pillbugs and sowbugs have microbes in their guts that allow the crustacean to digest plant material.

Some more information...

Some species of pillbugs and sowbugs that live in people's gardens have been accidentally transported all around the world, and are found on all continents.

University of Michigan Museum of ZoologyNational Science Foundation

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. "" (On-line), Animal Diversity Web. Accessed February 25, 2024 at

BioKIDS is sponsored in part by the Interagency Education Research Initiative. It is a partnership of the University of Michigan School of Education, University of Michigan Museum of Zoology, and the Detroit Public Schools. This material is based upon work supported by the National Science Foundation under Grant DRL-0628151.
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