Weakly Electric Fish Flashcards
What is significant about enigenmannia sp?
They have an electric organ composed of modified muscle cells
They are able to produce electrical fields as continual waves -they are weak electrical fields which are used for navigation and communication
Why do weakly electric fish have electric fields?
They use it to navigate and communicate in freshwater as their vision is not great
What do the modified muscle cells do in weakly electric fish?
Modified cells that lack contractile protein - they cannot contract to produce action potentials
These cells are found in the electric organ
How does the electric field work?
When fish swims around the electric field will be disturbed by objects around the fish meaning it will feel the disruption and be able to navigate through
What do strongly electric fields do?
They use strong waves as a defence mechanism
What is the behaviorual problem produced by the electric fields?
Jamming
How does jamming occur between the fish?
When two fish produce regular electric fields, they feel the combined electric organ discharge of their field and other fish combined and it creates a phase and amplitude modulate
(Change height and size of the waves)
When does the jamming occur between the fish?
When they are close to eachother and most interference acts within 20Hz
What is the response to avoid jamming?
If two fish encounter eachother with similar electric organ discharge, they will diverge from eachother:
The fish with the highest electric organ will raise it
The fish with the lower electric organ will lower it
What are electro receptors
They are made up of ampually receptors, tuberous receptors, p-type receptors
What are ampually receptors?
They detect direct current and low frequency
Slow and consistent signals detected
What are tuberous receptors?
They are interested in changing signals in the electric organ range -
They are tuned to AC signals
What are P type receptors
They are interested in amplitudes of waves
What are T-type receptors?
They are time coders and produced phase-locked spikes at the end of each signal
How do fish detect jamming P and T units?
The fish will fell their own electrical field symmetrical ly across the surface of body
If there is a neighboring fish it will ONLY feel the points that the neighbouring fish is obstructing
At this point it will feel both electrical fields in a oscillating pattern
