Hands On! Volume 17, No. 2, Fall 1994 (c) TERC, 1994. All rights reserved.

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The Behavioral Ecology of Brine Shrimp

by David Cash

A student comes into class one day describing what she considered a bizarre event. The previous night she had noticed swarms of moths, mosquitoes, and other flying insects gathering around her window where her desk lamp shined through. She moved the lamp to the opposite side of the window, and sure enough, the insects followed the lamp. "Why did they do this?" she asks. "Did all insects that could see the light come to it, or did only a few?"

Other students start chiming in with observations and questions about patterns of animal behaviors they had noticed. How did so 'many' ants find the dropped ice cream cone on the side-walk? How do migrating flocks of birds know where they are going? Soon the class is abuzz with observations, insights, and questions about the behavioral ecology of animals.

Understanding the way organisms behave in response to their environment is integral to understanding the ecology of those organisms. For example, senses are fundamentally important to how animals interact with both their biological and physical surroundings. Most senses like hearing, sight, smell, taste, and touch are familiar to us. Even though most animals have these same five senses, sensitivity to the stimuli vary greatly: dolphins and bats detect ultrasound; bees can see ultraviolet light; and some male moths have a sense of smell so acute they can sense the presence of one molecule of the female perfume pheromone. Other animals have senses that seem strange and unimaginable, like infrared detection in many snakes and electromagnetic sensing in fish.

Senses are used for finding food and shelter, for locating mates, for navigation and migration, for triggering hibernation, for communicating with other animals of the same and different species, and for avoiding predators. In short, animal senses are windows to the world around them. Knowing the senses and behaviors of an organism in response to its envi-ronment can advance students' understanding of its habitat, its relationship with other organisms, and its physical surroundings.

The activity that follows was developed as part of TERC's Institute for Teacher Development Through Ecology and encompasses the institute's goals of deepening ecological understanding and encouraging student-centered exploration. In a broad sense, the activity immerses students in a research question that allows them to pose and answer questions about the behavior and ecology of animals. More specifically, it engages students in a scientific process that enables them to explore the behavior of brine shrimp, Artemia salina.

Through their observations, students focus on "patterns" of behavior. They raise questions about observed patterns and about how such patterns relate to the ecology of brine shrimp in nature. Students design and implement investigations to address and attempt to answer their questions. Thus, this activity is a springboard from which students can examine the "ecological context" of behavioral patterns.

Overview of Activity

Brine shrimp are saltwater crustaceans related to freshwater fairy shrimp. They are not closely related to the shrimp we commonly eat. They are inexpensive and easy to hatch in a classroom, though difficult to raise to adulthood. Bought as adults, they are easy to maintain.

Brine shrimp display positive phototaxis; that is, the shrimp are attracted to and move toward light. Using brine shrimp in a classroom setting for an open-ended activity is particularly interesting because though students will quickly see that brine shrimp move toward light, they will pose other questions just as quickly. For example: Are the organisms attracted to heat? Do they prefer upper layers of the water column? Do they show preferences for light of different wavelengths?

These questions also apply to behavioral ecology. In a broader sense, How does being attracted to light help brine shrimp live? What is the function of phototaxis? Do brine shrimp feed on organisms that live in the upper layers of water? What does their behavior tell us about their habitat?

Given more time, students will generate even more questions that can be investigated relatively easily. Do young and old shrimp behave differently? How is hatching affected by salt concentration? pH? temperature? contaminants?

Clearly, unlimited opportunities exist for students to examine the interplay between the environment and the organism. The ease with which environmental factors and the brine shrimp can be manipulated in a classroom supports an open-ended approach that engages students in scientific inquiry, from asking questions to making predictions, designing experiments, and analyzing and presenting results.

Activity - Spotlight on Shrimp

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