AP Biology Vieira Pill Bug Lab Information on Pill Bugs: Classification "Pill bugs" or "Sow bugs" Armadillidium Valgare Phylum, Arthropoda; Class, Malacostraca; Order, Isopoda This group includes shrimp and crabs, they are not really "bugs". Appearance (Morphology) Color varies from dark gray to white with or without pattern Three body parts: head, thorax, abdomen One prominent pair of antennae (one inconspicuous pair) Simple eyes Seven pairs of legs Seven separate segments on thorax Paired appendages at end of abdomen called uropods On the underside, females have leaf-like growths at base of some legs. These brood pouches hold developing eggs and embryos. The first two appendages on the male abdomen are modified as elongated copulatory organs. Natural History Food Isopods are omnivores or scavengers feeding on dead or decaying plants or animals. Some may eat live plants. Habitat Isopods breathe with gills, so they are restricted to areas with high humidity, under rocks or logs, in leaf litter or in crevices. Some species are nocturnal. Predators Vertebrates and invertebrates. Interesting Behaviors Some species roll up into a ball when disturbed. Eggs (up to 100) are held in broad pouch on female. Juveniles look like adults and are soon liberated from pouch. Molting is in two stages. First the back half molts, then two to three days later, the front half molts. Coloration of both halves may be different at this time. Many species are fast walkers, but can be easily observed when held in the palm of the hand. Impact on the Ecosystem Positive In their immediate vicinity, isopods do minimal soil improvement. Isopods are also a food source for other animals. Negative In greenhouses and southern states, large populations can eat and damage plants. Where to find them Look under logs, moist leaf litter, flower pots (a day after they have been watered), outdoor pet dishes, and under paving bricks or stones. Isopods live where it is moist and usually in a shaded area. To attract them, water soil or leaf litter in the shade and cover with plastic, piece of plywood or cardboard. Keep the area moist and check under the covering in a couple days Introduction to Lab: Ethology is the study of animal behavior. This involves observing an organism’s behaviors, interpreting what is observed, and research different organisms. Ethologists study and observe an organism’s reaction to the environment around them. Biotic and abiotic factors are limiting factors that control the maximum size of a given population. Favorable conditions are desired by an organism of its home environment. Because of this, an animal must search for the environment to fit its structure and lifestyle. This is called habitat selection. An animal can display many different types of behaviors, two being taxis and kinesis. Taxis behaviors are deliberate movements toward or away from a stimulus. Kinesis is a random movement that is not oriented toward or away from a stimulus. Taxis behaviors are exemplary of the physiological needs of an organism. Other behaviors are agonistic (aggressive or submissive actions toward another organism) and mating behaviors. In today's lab we will examine the movement behavior of "Pill Bugs" Materials needed per group: 10 pill bugs, a shoe box, any materials needed to construct 4 different environments (dirt, water, light, leaves, grass, food etc) and a stopwatch. Procedure: 1. In order to create 4 environments for the pill bugs you will need to use a marker to mark the bottom of your shoe box into 4 equal squares. 2. Using any materials from outside or from home create 4 different environments for the pill bugs which will act as your different variables for the experiment. 3. Place the 10 pill bugs in the shoe box and count how many pill bugs you have in each of the 4 environments every 30 seconds for a half hour. Collect your data in a table and then graph it as a bar graph. Analysis Questions/Discussion 1. What conclusions can you draw from your data? Explain physiological reasons for the behavior observed in this activity. 2. How do isopods locate appropriate environments? 3. If you suddenly turned a rock over and found isopods under it what would you expect them to be doing? If you watched them for a few minutes how would you expect to see their behavior change? 4. Is the isopods’ response to moisture best classified as kinesis or taxis? Explain. 5. Write a conclusion of your experiment specific to your groups own findings.
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