Electroreception

a sensory modality known to exist for certain aquatic vertebrates which provides an ability to detect weak electric fields in water.  The origin of sensitivity may be traced to electroreceptors located in the skin of the organism.

Electroreception is limited to aquatic environments because on here is the resistivity of the medium is low enough for electric currents to be generated as the result of electric fields of biological origin.  In air, the resistivity of the environment is so high that electric fields from biological sources do not generate a significant electric current.  Electroreceptor are found in a number of species of fish,  and in at least one species of mammal,  the Duck-Billed Platypus.  It is generally believed to be an ancient sensory modality that is related to, and perhaps derived from, the lateral line sense.  Mammalian electroreceptors are independently derived.  Thresholds can be as low as 0.01 microvolts per cm for some species of fish.  Electroreceptors are rather insensitve to mechanical, light, chemical, and temperature.   There are specific behaviors associated with electroreception, which include prey detection and predator avoidance.  For those fishes with specialized electric organs, electroreception is also used for active object location and social communication.

Most animals do not have electroreceptors,  but they may respond to strong electric shocks which activate bare nerve endings, pain receptors and other sense organs, non selectively.  

Types of Electroreceptors
Type Where Found Sensitivity Structure
Ampullary Sharks & Rays;
Non-teleost fishes (except holosteans);
Certain teleosts (mormyrids, certain notopterus, gymnotiforms, catfish);
Amphibians (except frogs and toads).
0.01 microvolt per cm in marine species,  0.01 millivolt/cm in freshwater;  sensitive to DC fields or to frequencies less than 50 Hz
Tuberous Mormyrid fish (Knollenorgans,  Mormyromasts);
Gymnotiform fish (burst-duration coders,  phase coders)
0.1 mV to 10 mV/cm.

Figures modified from Szabo (1965).  R.C. = receptor cell;  b.m. = basement membrane;  n = nerve.  The ampullary receptor has a jelly-filled canal leading to the skin surface;  the tuberous recepor has a loose plug of epithelial cells over the receptor organ.


References on Electroreceptors

Historical

Bullock, T. H., Hagiwara, S., Kusano, K. and Negishi, K. (1961). Evidence for a category of electroreceptors in the lateral line of gymnotid fishes. Science 134, 1426-1427.

Fessard, A. and Szabo, T. (1961). Mise évidence d'un récepteur sensible à l'électricité dans la peau d'un mormyre. C. rendu hebd. Séanc. Acad. Sci. Paris 253, 1859-1860.

Lissmann, H. W. and Machin, K. E. (1958). The mechanisms of object location in Gymnarchus niloticus and similar fish. Journal of Experimental Biology 35, 457-486.

Szabo, T. (1965). Sense organs of the lateral line system in some electric fish of the Gymnotidae, Gymnarchidae, and Mormyridae. J. Morphology. 117, 229-250.

Reviews

Bullock, T. H. and Heiligenberg, W. (1986). Electroreception. In Wiley Series in Neurobiology (ed. R. G. Northcutt). New York: John Wiley & Sons Inc.

Hopkins, C. D. (1983). Functions and mechanisms in electroreception. In Fish Neurobiology, vol. 1 (ed. R. G. Northcutt and R. E. Davis), pp. 215-259. Ann Arbor: Univ. of Michigan Press.

Hopkins, C. D. (1983). Sensory mechanisms in animal communication. In Animal Behaviour 2: Animal Communication, vol. 2 (ed. T. R. Halliday and P. J. B. Slater), pp. 114-155. Oxford: Blackwell Scientific Publications.

EOD Recognition MODEL SYSTEMS