Chapter 6.2: Electroreception and Magnetoreception Flashcards
what is electrolocation?
the directional detection of external electric fields, typically short range, but permits function of animals in darkness.
uses of electroreception
good for light-limited environments (turbid freshwater, deep ocean, underground).
3 main evolutionary events that have led to the current adaptation of electroreception?
1) origins of specialized sense organs in a common ancestor
2) LOSS of specialized sense organs in a number of taxa (ex/ poor sight)
3) subsequent acquisition of sense organ in monotreme mammals (platypus) and a few teolosts.
2 main types of electroreception
1) passive electroreception: the ability to detect extraneous electric fields, but not their own currents
2) active electroreception: animals assess environment by actively emitting and receiving the feedback signal. They test the conductivity of water around them and locate perturbances by detection distortions produced in their OWN electric field.
____ electroreception is primarily used for electrolocation
passive
Example of mechanoreception
Ear hair cells use mechano receptors to detect sound. Sound waves cause the receptor to vibrate, inducing conformational change to the mechanical energy of the sound wave. This opens up a mechanically gated CHANNEL, causing an influx of Na+ and triggering an action potential in the afferent neuron
Example of chemoreception
sensors in the body that monitor oxygen levels are use chemoreceptors to detect O2 concentrations.
example of electroreception
Sharks have ampullae of Lorenszine electroreceptors that can locate prey by detecting faint potentials even through sediment.
The electroreceptor is gel filled and the current can travel through the gel to cilia, which triggers neurotransmitter release.
What do ampullary electroreceptors do?
responds to low frequency electric signals emitting from animal nerves and hearts. typically gel filled. The current travels thourhg the gel to cilia which triggers neurotransmitter relase.
In active electroreceptrion, how do fish produce their own electric current/field?
through their electric organ in their tail secion. it becomes negatively charged and produces an electric current.
in active electroreception, ____ electroreceptors lie in a lateral line system and monitor changes in local current flow. What are they responsive to?
tuberous electroreceptors lie in the lateral line system. Respondive to high frequency signals from the electric organ dischange.
the tuberous electroreceptors are distributed over the body to create ____ organized maps in the brain. What are these maps called?
somatotopically organized maps in the brain. these maps are known as the electrosensory lateral line lobe.
the electric organ is created by ____. How are these cells formed?
electrocytes. Electrocytes are derived from muscle tissue and stacked. They have electrolytes in series surrounded by insulating material
outline the mechanism of electric organ discharge
1) potential on the smooth side of the electrocyte is reversed by stimulation by spinal cord
2) causes current flow between cytoplasm and external medium
3) many electrocytes are excited in synchorny by nerves and the voltages add up because they are isolated from one another
4) results in an EOD randing from mV to V
2 type of fish that use electric organ discharges
1) pulse type fish: emit EODs at a low rate irregular intervals and accelerate and decelerate EOD rate to conserve energy and reduce predation
2) WAVE type fish: constantly emit EODs at high frequency
