Startle Displays And Flash Coloration

When stimulated by an aggressor, some protostomes quickly modify their posture to make them appear larger and at the same time to quickly present a "flash" of color. The various postures and displays are characterized by their position, such as frontal displays and lateral displays. The colors associated with these displays are often effective forms of defense because aggressors learn to associate certain colors with results that may have occurred through prior interaction with the intended prey. For example, if the prey had exhibited a certain color to its attacker, and then the predator became sick after ingesting the prey, or the intended prey sprayed the aggressor with a disagreeable fluid its body produces, the predator learns to associate that outcome with the flash of color it had seen and will attempt to avoid repeating the sit uation. Rapid display of color is also effective because the display itself will often frighten aggressors away. An example of a flash display is found in the katydids (Neobarrettia vannifera). When disturbed, this animal quickly opens its wings to reveal a polka-dot pattern. A display resembling a large face awaits any aggressor who disturbs the peanut bug, Laternaria later-naria (Fulgoridae), and flag-legged insects (Coreidae) quickly wave a brightly colored leg that it can afford to lose.

Learned behavior

The reasons for studying learning in protostomes are varied. Some scientists hope to exploit the nervous system of invertebrates in an effort to reveal the biochemistry and physiology of learning. Other scientists are interested in comparing invertebrates with vertebrates in a hunt for the similarities and differences in behavior. Still other scientists use learning paradigms to explore applied and basic research questions such as how pesticides influence honey bee foraging behavior and if learning is used in defensive and social behaviors.

A prerequisite for the study of learning is that be clearly defined and that the phenomena investigated as examples of learning be clearly defined. When reviewing studies of learning, the scientist should be aware that definitions vary from researcher to researcher. For example, a researcher may consider behavior controlled by its consequences (i.e., behavior that is rewarded or punished) as an example of operant behavior, while others believe that it depends upon the type of behavior being modified (either operant or instrumental learning). Moreover, some believe that any association between stimuli represents examples of Pavlovian conditioning, while others believe that the "conditioned stimulus" must never elicit the response to be trained prior to any subsequent association.

Here, learning is defined as a relatively permanent change in behavior potential as a result of experience. Several important principles of this definition include the following:

• Learning is inferred from behavior.

• Learning is the result of experience; this excludes changes in behavior produced as the result of physical development, aging, fatigue, adaptation, or cir-cadian rhythms.

• Temporary fluctuations are not considered learning; rather, the change in behavior identified as learned must persist as such behavior is appropriate.

• More often than not, some experience with a situation is required for learning to occur.

To better understand the process of learning in proto-stomes, many behavioral scientists have divided the categories of learning into non-associative and associative.

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