Pillbugs vs. Sowbugs. . .Which Do You Prefer?

Ms. Eckert's classroom is the home of many organisms.  There is Savannah (our leopard gecko), Clem (our albino axolotl), our many pillbugs as well as sowbugs, and many tiny microorganisms that we cannot see!  In the beginning of the year, there was a lab conducted by our biology class to observe the behavior of the species Armadillidium, commonly referred to as pillbugs.  The purpose was to evaluate what types of environments the pillbugs preferred to reside in.

Drawing copyright © 1997 R. Brusca.

Pillbugs are classified in the order of Isopoda which include crustaceans that range in various shapes and sizes.  Isopods are commonly mistaken as insects due to the fact that they are small and live in the ground, however, they are terrestrial crustaceans.  As in most crustaceans, the isopod body is divided into three distinct regions of the head (cephalon), thorax, and abdomen (pleon).  The first segment of the thorax is fused to the head.  There are usually seven free segments called pereonites of the thorax that make up the pereon.  They also have compound eyes, two pairs of antennae, and four sets of jaws.  Isopods also are found in marine and terrestrial habitats as well, but most of these creatures live in water.  Common marine crustaceans include lobster, crab, krill, shrimp, and barnacles.  Crustaceans respirate through gills that are located where the legs attached to the thorax. 

Before actually starting the experiment, the biology class compared the differences between two terrestrial crustaceans, pillbugs to sowbugs.  Pillbugs and Sowbugs are recognized by their wingless, slate­ grey colored, round­-back, bodies that have segments which resemble armored plates.  Their oval bodies are convex above but flat underneath.  They also have seven pairs of legs and two pairs of antennae, although one pair is barely visible.  Sowbugs, the species Porcellionidae, are typically larger than pillbugs and also have two tail-like appendages that jet out at the rear end of the body.  Since pillbugs do not have these appendages, it allows them to roll up into a tight ball when disturbed - hence the name "rolly-polies."

 Can you identify which ones are sowbugs and which ones are pillbugs?

Pillbugs and sowbugs are found in moist environments, commonly outdoors.  Occasionally, they will end up in buildings but have no fear if you find them in your house!  They may be found in large numbers but these bugs do not bite, sting, or transmit diseases.  Indoor environments are often too dry so the pillbugs and sowbugs will die soon after coming inside.  Both species play a role in the cycling of nutrients as they feed mainly on decaying organic matter.  They can only thrive in environments of high moisture such as damp areas under objects.  Around buildings and playgrounds are common areas to find them.  Do you remember digging in the ground when you were younger and finding rolly-pollies in the soil? I hope that I wasn't the only kid who did that.

I personally like pillbugs and because they are a lot calmer than sowbugs.  When I let a pillbug walk across my hand, it takes its time to crawl and I get a chance to see its physical characteristics.  I also think its really cool that pillbugs can curl up into balls - c'mon they even got a good name for themselves!  Sowbugs are a bit bigger and more aggressive when traveling.  They like to move quickly and are more frantic.  When I placed a sowbug in my hand, it kept trying to run away and eventually just fell off my hand. 

Here is one of the class's pillbugs! (left: curled up, right: crawling)

Now let me show you a sowbug (left: crawling OFF my hand, right: back in its habitat)

So although pillbugs and sowbugs are pretty similar. . .which do you prefer?

A Day in the Life of Savannah

          One of the most well known organisms inside Mrs. Eckert's classroom is Savannah, our leopard gecko (Eublepharis macularius). Savannah is our class's pride and joy. She helps de-stress students when we are nervous about an upcoming test, she entertains students by excreting wastes on students, and is just a fun pet for us scientists to explore. Savannah loves to eat super worms! Mrs. Eckert first got Savannah for her freshman students in 2 years ago. At first she wasn't surviving that well, but due to all the student's love and wonderful crickets, she is now surviving great!
          The leopard gecko is originally from the deserts of Asia, throughout Pakistan, and Northern India. During the winter in these areas, the leopard geckos go underground into a semi-hibernation (otherwise known as brumation), where the geckos live on fat reserves (which is stored in their weird tail). In the wild, leopard geckos are crespuscular species which means that they are forced to live in the burrows during the day, but become active at dusk/dawn when the temperature is more favorable. Recently, the leopard gecko has become domesticated. Leopard geckos are thought to be the first domesticated lizard species. 
          Leopard geckos are also bred in captivity, like most other domesticated animals. This means that many people choose a favorable phenotype, so the breeders artificially select that phenotype. Some of these phenotypes include: three different strains of albino, patternless, blizzard, jungle, hypomelanistic, tangerine, giant, and snow. Savannah, however, is none of these strains. 

          The leopard gecko also exhibits sexual dimorphism, which is a phenotype difference between males and females. This is how someone determines the sex of a gecko, which can only be done when they are adults. Female geckos, like Savannah, have smaller pores on their underside and do not have any budges; males have pre-anal pores and hemipenal bulges. Males can identify other geckos by smelling pheromones on their skin. Males respond to other males aggressively, however they respond to females in a friendlier manner (I mean who wouldn't, look at how beautiful Savannah is!) Males and females also have temperature-dependent sex determination. This means that a female gecko is more likely to have a girl if it is in a certain temperature than a boy. Savannah was probably born in either very cold or very warm temperatures (79–84 °F or 93–95 °F). This determination was probably set during two weeks of incubation. 
          Savannah typically has a very exciting day during the school year. She wakes up bright and early with period one AP Bio. They usually are a little cranky due to zero period lab, or the 8 o'clock class start, so Savannah has a quiet morning. She then goes through the day hanging out with Mrs. Eckert and other classes like Anatomy and Physiology. Her day really starts with the start of period 7, where Mrs. Eckert's other AP Bio class comes in. Savannah comes out and hangs out with all the tables, crawling inside binders and on top of classmates heads. Savannah's favorite topic was learning about all of the scientists, her favorite being Rosalind Franklin. Savannah is so popular she even has friends in other classes. One of her best friends, or mother has she likes to believe, is actually a sophomore who has never even been in Mrs. Eckert's classes! She loves taking Savannah home over breaks and probably checks in on her as much as the other students. Savannah is one popular gecko!