Alarm signals avoidance

Predator attraction as a strategy favoring senders would favor chemical secretions that were easily detected by predators. Both alarm signaling and predator attraction should favor easy detection. However, there could be conflict between attracting predators and repelling conspecifics, so a compound or mix of compounds that was a general attractant or repellant would favor one function over the other. If that is so, predator attraction seems to have won out in fathead minnows. However, compounds that attract predators are best avoided by prey, increasing selection on prey for defensive responses to the cue. 

The evolutionary success of the aphid appears closely linked to the development of chemical alarm signals and the cornicle. The primitive Aphidoidea that lack or have poorly developed cornicles have adopted a strategy of predator avoidance most live within protective plant galls or are soil dwellers. There is a strong correlation between presence of well-developed cornicles in aphids and their exposed habitat. One of us (L.R.N.) discovered what may represent an evolutionary primitive form of aphid alarm communication. Hamamelistes spinosus, a Hormaphidinae that lacks cornicles, releases low levels of alarm chemicals from its punctured body wall. The aphid lives within cupped birch... 

Olfaction, the sense of smell, is an important neural system in various animal species, including fish, for their life. Fish can detect a variety of odorants emitted from objects and dissolved in the water, such as amino acids, bile salts, nucleotides, polyamines, prostaglandins, and steroids. The fish olfactory system is extensively developed to receive and discriminate these odorant molecules, to transmit their signals to the brain, and to mediate fundamental behaviors such as food finding, alarm response, predator avoidance, social communication, reproductive activity, and spawning migration (Sorensen and Caprio 1998 Zielinski and Hara 2007). 

It has been known for many decades that odors influence animal behavior, including foraging, predator avoidance, alarm response, social dominance, cohort recognition, and courtship. Darwin (1871) initially proposed chemical signals as a key mechanism in mate choice by which sexual selection is promoted. However, it was not until the discovery of the silkworm moth pheromone bombykol by Butenandt et al. (1959)... 

The criticality accident diat is expected to be signaled by the alarm system may have widely varying characteristics, depending bn the form and type of fissile material and oh the initiating mechanism. Solution accidents, clearly the most probable for process areas, have a rise time limited by the neutron lifetime, which is on the order of milliseconds. While accidents involving metal or dry compbunds are easier to avoid, the shorter neutron lifetime and faster rise time of the excursion lead to much... 

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