Alarm odors

An animal can control release of odor molecules from body surfaces, especially skin gland areas, up to a point. But in moist air, volatiles from secretions on skin or hair will evaporate more easily. If only intermittent odor emission is desirable, humidity would interfere with the animal s odor release. Glands that produce such intermittent signals, such as alarm odors, appear to be more developed in species or subspecies in drier climates. An example is the metatarsal gland in... 

In addition to behavior changes, exposure to the alarm odor also has physiological effects. For instance, in pearl dace, Semotilus margarita, the levels of plasma cortisol and glucose increase 15 minutes after the alarm and are back to normal after 5 hours. The brain concentrations of dopamine, norepinephrine, 5-hydroxytryptamine, or tryptophan did not change (Rehnberg et al., 1987). The fish recovered physiologically much sooner than the behavioral activation For example. Von Frisch (1941) observed that minnows avoided the site of their encounter with alarm substance for many hours, even days. 

Some taxa may possess pheromone-producing tissues, while others have similar tissues but without pheromones. At the cellular level, extensive comparative studies of fish alarm responses show that cyprinids possess club cells, which release an alarm odor when ruptured by a predator attack. Polypteriformes have... 

Predatory fish may also be affected by alarm pheromones (Section 7.2) of the prey, both directly and indirectly. The alarm odor may act as defense compoimd that inhibits predator attack or reduces capture rate by inducing predator avoidance in school members of the prey species. 

The purpose of this experiment is to examine the role of ants in the life of aphids. Although chemical stimuli play an important role in their interactions, here we focus on the results of these interspecific behaviors. Nevertheless, the observer can try to gently touch an aphid with a pair of fine tweezers and observe the responses of ants and other aphids over a distance, presumably in response to an alarm odor. 

Briones-Fourzan P (2009) Assessment of predation risk through conspecific alarm odors by spiny lobsters. Commun Integr Biol 2 302-304... 

Briones-Fourzan P, Ramfrez-Zaldivar E, Lozano-Alvarez E (2008) Influence of conspecific and heterospecific aggregation cues and alarm odors on shelter choice by syntopic spiny lobsters. Biol Bull 215 182-190... 

The chemicals that indicate an increased risk of predation can come from several sources. Perhaps the most widespread are chemicals released by physical damage to a conspecific crustacean. Almost every species tested has shown an increase in behavior patterns that can be related to predation avoidance when odors of crushed conspecifics are presented. There is no indication of crustaceans having specialized cells such as the epidermal club cells (the previously purported source of alarm odor in the narrow sense) found in ostariophysan fish (Smith 1989,1992). But rather some chemical or chemicals, very probably including peptides, found in the hemolymph seem implicated as the cue in crustaceans (Rittschof et al. 1992 Rittschof 1993 Rittschof and Cohen 2004 Acquistapace et al. 2005), as well as in... 

Fig. 18.5 Duration of the antipredator limb-spread posture by individuals of H. rotundifrons depending upon treatment prior to the tactile induction of the posture. Mean ( SE) in seconds under control conditions, addition of alarm odor, passage of shadows, and the combination of alarm odor and shadows (data from Hazlett and McLay 2005a)...

Acquistapace P, Daniels WH, Gherardi F (2004) Behavioral responses to alarm odors in potentially invasive and non-invasive crayfish species from aquaculture ponds. Behaviour 141 691-702... 

Hazlett BA (2000b) Information use by an invading species do invaders respond more to alarm odors than native species Biol Invasions 2 289-294... 

Hazlett BA (2003a) The effects of starvation on crayfish responses to alarm odor. Ethology 109 587-592... 

Supplemental measures that may be considered are a fixed oxygen monitoring system, a low pressure storage bottle alarm(s) or odorization of the stored CO2 gas. 

Dimercaprol (British Anti-Lewisite or BAL) is a colorless, viscous oily compound with an offensive odor used in treating arsenic, mercury, and gold poisoning. It displaces the arsenic bound to enzymes. The enzymes are reactivated and can resume their normal biological activity. When given by injection, BAL can lead to alarming reactions that seem to pass in a few hours. 

Even if the subject makes the most sensible choice, putting his criterion at Cl in figure 1, he will still make a number of false alarms and misses. If, in this case, the experimenter tells him that at times he is giving positive responses to odourless presentations (false alarms) the subject will be induced to shift his criterion to the right (C2). As a result he will very seldomly give a false alarm, but at the same time he will say no to more than half of the odorous stimuli presented to him. 

FIGURE 2.5 Visual signal is combined with odor release when an alarmed pronghorn Antilocapra americana) flares his "rump patch of long hair covering the ischiadic gland. (Photograph D. Miiller-Schwarze.)... 

Other examples of stimulus generalization are the alarm chemicals in salamanders (Mason and Stevens, 1981a) and behaviorally irrelevant pure odors (Braun and Marcus, 1969). 

Chapter 6 discussed signaling pheromones that allow discrimination, recognition, and broadcasting dominance and territorial status. This chapter explores the role of pheromones and other odors in reproduction, alarm, trail following, and in connection with food. Some evolutionary considerations conclude the discussion of signaling pheromones. 

Particularly alarming are fetal effects of alcohol and drugs on food-related odor responses in humans. Apart from the severe fetal alcohol syndrome, alcohol can affect the chemosensory behavior of a fetus. Alcohol administered to pregnant female rats impaired odor aversions and preferences in their offspring. A... 

Fish avoid more vigorously the odor of predators that have fed on members of their species than that of those on different diets. For example, young Arctic chart avoid water from brown trout fed on Arctic chart and are less wary of that from pellet-fed trout (Hirvonen et ah, 2000). Prey fish also reduce their predator inspection behavior vis-a-vis predators that have eaten members of their own species. For instance, finescale dace, Phoxinus neogaeus, dash toward predators such as yellow perch, Percaflavescens, and withdraw. Dace inspect perch models less often if the model is accompanied by water from perch that had eaten dace than if accompanied hy water from perch on a swordtail, Xiphophorus hdleri, diet. Dace produce alarm pheromone, while swordtails do not. The Central American swordtails do not cooccur with finescale dace (Brown etal, 2001). 

In minnows, taste is not sufficient for predator recognition. Anosmic fathead minnows, P. pmmelas, did not show the flight reaction to the odor of northern pike, Esox lucius (Chivers and Smith, 1993). Naive European minnows, Phoxinus phoxinus, do not exhibit a fright reaction when first exposed to a predator odor, such as that of pike, E. lucius. They develop a conditioned fright response only after experiencing the predator odor in dangerous circumstances, such as when accompanied by schreckstoff (alarm pheromone) of conspecifics. Responses to the odor of non-piscivorous fishes such as tilapia, Tilapia mariae, can also be conditioned in this fashion but the responses are much weaker (Magurran, 1989). 

In their predator avoidance, salamanders use complex odors that combine chemicals from both predator and prey. In the laboratory, red-backed salamanders, P. cinereus, avoid filter papers soaked with water extracts from garter snakes that had been preying on salamanders, while earthworm-fed snakes lacked this effect. Exudations from unfed snakes and extracts from homogenized salamanders had no such alarming effect (Madison etal, 2002). 

Many species of astigmatid mite emit species-specific alarm pheromones when they are disturbed. This is easily demonstrated by the species-specific odor change produced upon shaking a petri dish of mites. This odor change can be documented more methodically by comparing the profile of volatiles produced by undisturbed and disturbed colonies. For example, disturbed colonies of the mold mite T. putrescentiae were found to produce an average of 102 times as much of the alarm pheromone neryl formate (1) as undisturbed colonies (Kuwahara et al., 1979). 

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