Fish Lateral Line System Quiz and Flashcards ch4

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Questions and Answers

What is the significance of the concentration of sensitivity to water motion in the head region of some fish?

It is important for sensing vortex trails in the wakes of adjacent fishes in a school.

What is the advantage of having reduced lateral line elements along the flanks of some fish?

It reduces noise from turbulence beside the fish.

How do electric fishes generate electrical discharges?

Through modified muscle tissue called electrocytes that are specialized for generating an ion current flow.

What is the resting state of the membranes of muscle cells and nerve cells in electric fishes?

The intracellular fluids are about 84 millivolts more negative than the extracellular fluids. Signup and view all the answers

What is the function of electrical signals in weakly electric knife fishes and elephant fishes?

They are used for courtship and territorial defense. Signup and view all the answers

What is the purpose of electrical discharges in torpedo rays, electric catfish, and electric eels?

To stun prey animals and deter predators. Signup and view all the answers

What is the primary reason for the imbalance of ion concentrations across the electrocyte membrane?

sodium ion exclusion Signup and view all the answers

What is the potential difference across the cell when the smooth surface is depolarized?

151 millivolts Signup and view all the answers

How do the electrocytes in the electric eel generate high voltages?

The electrocytes are arranged in stacks, and the potentials of many layers of cells combine to produce high voltages. Signup and view all the answers

What is the maximum voltage that the South American electric eel can generate?

in excess of 600 volts Signup and view all the answers

Which marine fishes are capable of generating specialized electrical discharges?

The torpedo ray (Torpedo), the ray genus Narcine, and some skates. Signup and view all the answers

What is the function of the spinal motor neurons in the electric eel?

They stimulate the electrocytes to generate an electric discharge. Signup and view all the answers

What is the primary mechanism by which weakly electric fishes detect the presence of nearby objects?

They detect distortion of the lines of electrical force through electroreceptors in their skin. Signup and view all the answers

How do nonconductive objects, such as rocks, affect the electric field surrounding a weakly electric fish?

They spread the field and diffuse potential differences along the body surface. Signup and view all the answers

What is the likely origin of electroreception in vertebrates, based on the presence of electroreceptor cells in early fishlike vertebrates?

Electroreception was probably an early feature of vertebrate evolution. Signup and view all the answers

What is the significance of the kinocilium in electroreceptor cells?

The cells fire when the environment around the kinocilium is negative relative to the cell. Signup and view all the answers

What is the region of the brain where impulses from electroreceptor cells are processed?

The midline region of the posterior third of the brain. Signup and view all the answers

What is the significance of the frequency change in electric fish when they swim close to each other?

It indicates interference between their electric fields. Signup and view all the answers

What unique feature of seawater allows sharks to detect the electrical activity of their prey?

The high conductivity of seawater Signup and view all the answers

What is the role of the gel in the canal connecting the receptor to the surface pore in the ampullae of Lorenzini?

It is electrically conductive Signup and view all the answers

How do the electroreceptors of sharks respond to changes in the electric field surrounding an animal?

They act like voltmeters, measuring differences in electrical potentials across the body surface Signup and view all the answers

What type of nerve cells produce extremely brief changes in electrical potential, contributing to the detection of prey by sharks?

Motor nerve cells Signup and view all the answers

What is the significance of the threshold of detection of less than 0.01 microvolt per centimeter for the ampullary organs of sharks?

It indicates an extremely high sensitivity, comparable to the best voltmeters Signup and view all the answers

What type of activity generates electrical potential changes that sharks can detect using their electroreceptors?

All muscle activity Signup and view all the answers

What is the effect of deflection of the kinocilium in one direction on the hair-cell transmembrane potential?

Depolarization of the cell and increased discharge rate (excitation) Signup and view all the answers

What is the purpose of the cupula in the lateral line system?

To detect water currents and determine their direction on different surfaces of the fish's body Signup and view all the answers

What is the function of the neuromast organ in the lateral line system?

To detect water currents and transmit signals to the nerve Signup and view all the answers

How do the hair cells in a pair signal the direction of cupula displacement?

Each hair-cell pair signals the direction of cupula displacement by increasing the firing rate in one afferent nerve and decreasing it in the other nerve Signup and view all the answers

What is the effect of deflection of the kinocilium in the opposite direction on the hair-cell transmembrane potential?

Hyperpolarization of the cell and reduced discharge rate (inhibition) Signup and view all the answers

What is the significance of the lateral line system in fish?

To detect and respond to water currents on different surfaces of the fish's body Signup and view all the answers

Study Notes

Sensing and Electric Discharge in Fish

Some fish have a large number of neuromasts on their heads, which might be important for sensing vortex trails in the wakes of adjacent fish in a school.
Fish that form extremely dense schools, such as herrings, atherinids, and mullets, often lack lateral line organs along their flanks and retain canal organs only on their heads.
These cephalic canal organs concentrate sensitivity to water motion in the head region, allowing the fish to sense the turbulence it is swimming into.
The reduction of flank lateral line elements reduces noise from turbulence beside the fish.

Electric Fish

Electric fish, such as the torpedo ray, electric catfish, and electric eel, can discharge enough electricity to stun prey animals and deter predators.
Weakly electric fish, such as the knife fish and elephant fish, use electrical signals for courtship and territorial defense.
These fish use modified muscle tissue to produce the electrical discharge, which is generated by specialized cells called electrocytes.
Electrocytes are muscle cells that have lost the capacity to contract and are specialized for generating an ion current flow.
When at rest, the membranes of muscle cells and nerve cells are electrically charged, with an imbalance of 84 millivolts due to sodium ion exclusion.
When stimulated, sodium ions flow rapidly across the smooth surface, sending its potential to a positive 67 millivolts, resulting in a potential difference of 151 millivolts across the cell.

Electric Discharge in Fish

Electric fish have stacks of electrocytes, which combine to produce high voltages.
The South American electric eel has up to 10,000 layers of cells and can generate potentials in excess of 600 volts.
Most electric fish are found in tropical freshwaters of Africa and South America, with few marine forms capable of generating specialized electrical discharges.

Electroreception in Other Vertebrates

Electroreception is not restricted to a single group of aquatic vertebrates, and monotremes, such as the platypus and echidna, use electroreception to detect prey.
Electroreception was likely an early feature of vertebrate evolution, with the brain of the lamprey responding to electric fields.
All fish-like vertebrates of lineages that evolved before the neopterygians have electroreceptor cells, which fire when the environment around the kinocilium is negative relative to the cell.

Electroreception in Sharks and Rays

Sharks have electroreceptors called the ampullae of Lorenzini on their heads, which detect the electrical activity that accompanies muscle contractions of their prey.
The ampullae are sensitive to minute changes in the electric field surrounding an animal, with thresholds lower than 0.01 microvolt per centimeter.
Sharks use their electrical sensitivity to detect prey, as all muscle activity generates electrical potential.
The ampullae act like voltmeters, measuring differences in electrical potentials across the body surface.

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Description

This quiz covers the anatomy and function of the lateral line system in fishes, including the structure of neuromast organs, hair-cell receptors, and nerve impulses. Test your understanding of this complex sensory system.

Lateral Line System in Fishes ch4 2

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