Iowa darters

Other water-dwelling animals such as crayfish, hermit crabs, and a fish called the Iowa darter also have been observed to send chemical danger signals when they are threatened. Scientists think that the chemical used to send the signal is the ammonium ion, Researchers are now trying... 

Wisenden BD, Chivers DP, Smith RJF (1995) Early warning in the predation sequence a disturbance pheromone in the Iowa darter (Etheostoma exile). J Chem Ecol 21 1469-1480 Yambe H, Kitamura S, Kamio M, Yamada M, Matsunaga S, Fusetani N, Yamazaki F (2006) L-... 

Smith, R. J. F., 1981, Effect of food deprivation on the reaction of Iowa darters (Etheostoma exile) to skin extracts, Can. J. Zool. 59 558-560. 

Chivers, D. P., Wisenden, B. D., and Smith, R. J. F., 1995, The role of experience in the response of fathead minnows Pimephales promelas) to skin extract of Iowa darters Elheosloma exile). Behaviour 132 665-674. 

The effectiveness of the overt fright reaction as defense has been demonstrated in fathead minnows Pimephales promelas) where the overt responses decrease an individual s vulnerability to predation by pike in laboratory tanks (Mathis Smith 1993b). There is also evidence that the overt responses are often contingent on other variables. For example, both Iowa darters (Etheostoma exile) (Smith 1981), which are not ostariophysans, and fathead minnows, which are, (Brown Smith 1996) show a reduction or absence of overt responses when foraging tradeoffs are increased by 48 hours of food deprivation. Common shiners Luxilus cornutus) vary their responses to alarm pheromones according to whether they detect an aquatic or avian predator in the vicinity (Heczko 1980). 

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