Knollenorgan
electric organ
. The returns from the pulses, distorted by any nearby objects such as prey, are detected by the knollenorgans distributed around the fish's body.A Knollenorgan is an
electroreceptor in the skin of weakly electric fish of the family Mormyridae
(Elephantfish) from Africa. The structure was first described by Viktor Franz (1921), a German anatomist unaware of its function. They are named after "Knolle", German for "tuberous root" which describes their structure.
Structure and function
Knollenorgans contain modified epithelial cells that act as sensory transducers for electric fields. Besides these, there are supporting cells and a sensory neuron. The neuron projects to the fish's brain, specifically to the nucleus of the electrosensory lateral line lobe (nELL) of the medulla via the posterior branch of the lateral line nerve.[2][3][4][5]
The organs are embedded in the thickened
sensory receptors, allowing capacity-coupled current to pass from the external environment to the sensory receptor.[2][3][4][5]
Knollenorgans lack the jelly-filled canal leading from sensory receptor cells to the external environment characteristic of the
basal groups of fishes. Knollenorgans are sensitive to electrical stimuli at frequences between 20 hertz and 20 kilohertz, with electric fields as small as 0.1 millivolt per centimetre. They are used to detect the weak electric organ discharges of other electric fish, usually of their own species.[2][3][4][5]
See also
- Ampullae of Lorenzini – the ancestral type of electroreceptor in vertebrates
References
- ^ a b Franz, Viktor J. (1921). "Zur mikroscopischen Anatomie der Mormyriden" [On the Microscopic Anatomy of the Mormyrids]. Zoologisch Jahrbuch Abteilung für Anatomie und Ontogonie (in German). 42: 91–148.
- ^ PMID 5219479.
- ^ .
- ^ S2CID 33838224.
- ^ ISBN 978-3-642-65928-7.