Fish use their lateral line system to detect water movement.
The receptors in the lateral line consist of mechano-sensitive hair cells that are deflected by waterflow.
Our inner ear and electroreceptive organs in certain fish are evolutionary derived from the lateral line organs.
Gnathonemus petersii and
are three electric fish that live in Southeast Asia, West Africa and South America respectively. The bodies of these fish are covered with small organs, 'small pits', that are stimulated by weak electric fields such as those generated by prey animals. While the glass catfish Kryptopterus locates prey by sensing their electric fields, Gnathonemus and Apteronotus generate an electric field using discharges by modified muscle cells located in their tails. Because prey and other objects deform the electric field, these two fish are able to orient themselves even in muddy water.
The photo shows a transparent small pit of Kryptopterus with a glass electrode and nerve activity that is generated at the bottom of the pit (left) below the sensory epithelial cells. One of those sensory cells is touched by the electrode tip.
(Electric recordings courtesy of Dr. F.Bretschneider, department of biology, university of Utrecht, Netherlands).
An interesting piece of music featuring Gnatonemus, 'Electric courtship', has been made by Frederik de Wilde.
is based on recordings from primary neurones that contact mechano-sensitive hair cells in a semicircular canal of the turtle Pseudemys scripta elegans:
The inner ear contains three orthogonal semicircular canals that are filled with endolymph. When the head rotates, the endolymph tends to catch up only slowly with the movement due to inertia. Hence, the canal wall moves with respect to the endolymph causing mechano-sensitive hair cells in the ampulla to be deflected. These cells contain potassium ion channels the opening of which depends on stretch of the plasma membrane. Entry of potassium ions into the hair cell causes an increase of the release of the neurotransmitter, glutamate that excites primary neurones. While dancing a walz, these neurones are stimulated rhythmically.
(Electric recordings courtesy of Dr. J. Bonsacquet, Institut des Neurosciences, Montpellier, France)
'Jumping motoneurones' has been created with electrical activity of rat (rattus norwegicus) motoneurones in culture and my electrocardiogram (ECG):
The sinoatrial node generates an electrical impulse that spreads through the atria thus causing depolarisation and contraction of the atria (P wave). After a short delay the impulse reaches the atrioventricular bundle of His (in orange) that conducts it to the bottom of the ventricles and depolarises the mucle cells (QRS waves, the Q wave is absent in the ECG shown). Hence ventricular contraction starts at the bottom and then moves up. After a short pause the ventricle repolarises and relaxes (T wave).
Motoneurones lie in the ventral part of the spinal cord and send their axons to target tissue such as muscle.
It is their activity that makes us walk, dance or jump. In the present work I've tried to translate electrical recordings of motoneurones into a rhythmic musical piece.