Ichthyology Exam 3 Review

Fish respiration, reproduction, and responses to gravity/motion.

How do fish breathe underwater?

Fish breathe underwater using gills, which extract oxygen from water.

When did gills first appear in the fossil record?

Gills appeared in the fossil record approximately 575 million years ago.

What was the primary selective pressure shaping early vertebrate gill evolution?

Efficient acid-base regulation, rather than oxygen uptake.

What is the major respiratory organ in fish?

Gills.

What is the difference in oxygen content of the medium on inspiration between aquatic and aerial environments?

Aquatic: 0 to 10 ml/l; Aerial: 210 ml/l.

What is the viscosity of water compared to air?

Water is between 35 and 100 times more viscous than air.

What is the primary method of ventilation in fish?

Continuous ventilation.

What type of fish are known to lack gills?

Leptocephalus larvae of species like Aguilla, bonefish, and tarpon.

What is unique about 'white-blooded' icefish?

They lack hemoglobin and pick up oxygen across skin and gill surfaces.

What are the two methods of ventilation used by hagfish?

Pharyngo-cutaneous duct and olfactory sac.

How do elasmobranchs ventilate their gills?

Through a combination of mouth and spiracle openings.

What anatomical feature supports the gill pouches in lampreys?

A branchial basket.

What is the benefit of counter-current oxygen exchange in fish gills?

It allows nearly complete extraction of oxygen from water.

What is the role of the operculum in bony fish respiration?

It helps maintain a one-way flow of water over the gills.

What is the difference in oxygen utilization between aquatic and aerial environments?

Aquatic: Up to 95%; Aerial: 25%.

What is the significance of the distance between lamellae in fish gills?

It affects the efficiency of gas exchange.

What happens during Phase I of gill ventilation in fishes?

The buccal pump expands, creating slightly negative pressure, allowing water to flow across the gills.

What occurs in Phase II of gill ventilation?

The buccal pump compresses, creating slightly positive pressure, while the opercular pump expands, maintaining water flow.

What is the result of the counter-current exchange mechanism?

It maximizes oxygen absorption from water as blood flows in the opposite direction.

How do fish achieve high oxygen driving pressure across the respiratory membrane?

Through large, highly vascularized respiratory surfaces.

What is the role of oxygen-binding respiratory pigments in fish?

They facilitate oxygen transport in the blood.

What anatomical feature allows hagfish to perform cutaneous respiration?

Hagfish skin is capable of gas exchange.

What is the primary function of gills in fish?

Gas exchange and acid-base regulation.

What adaptations do 'white-blooded' icefish have to compensate for lacking hemoglobin?

Large hearts, high blood volume, and increased mitochondrial density.

What is the significance of the high density of water compared to air for fish respiration?

It requires specialized adaptations for efficient gas exchange.

What happens during Phase III of gill ventilation?

The buccal pump compresses further, creating positive pressure, facilitating water flow across the gills.

What is unique about the buccal funnel in lampreys?

It is not used for inspiration and is not attached to the branchial basket.

What is the primary function of gill ventilation in fishes?

To facilitate gas exchange by moving water across the gills.

What are the two main pumps involved in fish gill ventilation?

The buccal pump (pressure) and the opercular pump (suction).

Describe the effect of the buccal pump during Phase I of ventilation.

The buccal pump expands with the oral valve open, resulting in slightly negative pressure.

What happens during Phase II of fish gill ventilation?

The buccal pump compresses with the oral valve closed, creating slightly positive pressure.

In Phase III of gill ventilation, what is the result of the buccal pump's compression?

The pressure becomes very positive, pushing water across the gills.

What adaptation allows goldfish and crucian carp to survive without oxygen?

They can convert carbohydrates into alcohol using specific enzymes.

What is the significance of the parabranchial pump in elasmobranch ventilation?

It acts as a suction pump, creating more negative pressure than the oropharyngeal pressure.

What is gynogenesis in fish reproduction?

A type of reproduction where eggs develop without fertilization, seen in live-bearing Amazon mollies.

What are the three types of reproduction found in fishes?

Bisexual, hermaphroditic, and parthenogenetic.

What distinguishes true functional hermaphroditism in fish?

Both male and female reproductive organs are present in one individual.

How do hormonal cues affect fish reproduction?

They trigger changes in both male and female fish to facilitate reproduction.

What is the role of the bucco-opercular cavity in fish respiration?

It is heavily vascularized to aid in gas exchange.

What is the effect of ventilation/perfusion mismatch in fishes?

It can lead to inefficient gas exchange and reduced oxygen uptake.

What is a 'shunt-like' effect in fish physiology?

Changes in blood and water flow that mimic a shunt, affecting gas exchange efficiency.

What is the primary challenge in gas exchange for fishes?

The efficiency of counter-current gas exchange is not 100%.

What adaptations do crucian carp have for predator evasion?

They can morph into a round disc shape and use camouflage.

What is the significance of the mudskipper's circulatory system?

It conforms to typical teleost configuration, allowing for both aquatic and aerial gas exchange.

What happens to water flow across gills during Phase IV of bony fish ventilation?

Water flow slows but does not stop as both pumps operate out-of-phase.

How do fish reproductive systems change in response to environmental cues?

Hormonal changes lead to reproductive readiness and spawning behaviors.

What is the impact of blood-water epithelial barrier in fish?

It offers resistance to diffusion, affecting gas exchange efficiency.

What is the role of the opercular cavity during fish ventilation?

It helps create negative pressure to draw water across the gills.

What is sexual reproduction in fish?

The union of sperm and eggs, typically requiring both male and female partners.

How long does it take for fish to reach sexual maturity?

It varies by species; some reach maturity in one year, while others may take up to five years.

What is 'mass spawning' in fish?

The simultaneous and synchronous spawning of most of a mating aggregation, characteristic of several species.

What is the common name for the fish genus Gadus?

Cod.

How many eggs can a single cod produce in one spawning event?

Up to 9,000,000 eggs.

How many eggs can the ocean sunfish produce in a single season?

28,000,000 eggs.

What is a salmon run?

An annual fish migration where salmon swim back upstream to spawn in freshwater.

What is broadcast spawning?

A method where fish release gametes into the water with no parental care.

What is semelparity in fish?

A reproductive strategy where both males and females die shortly after spawning.

What is mouthbrooding in fish?

A strategy where offspring are held in the mouth of the parent for extended periods.

Which family of fish is known for sex role reversal during reproduction?

Family Sygnathidae, which includes sea horses.

What is the role of the labyrinth inner ear in fish?

It helps fish detect gravity and motion.

What are the two main parts of the fish inner ear?

Pars superior and pars inferior.

What is the function of the utricle in fish?

It is the major endorgan of postural control.

What do the semicircular canals in fish detect?

Movement in three-dimensional space.

What is the cupula in the context of fish anatomy?

A deformable membrane in the semicircular canals that detects angular velocity and acceleration.

What is the significance of otoliths in fish?

They play a crucial role in balance and orientation.

How do fish respond to gravity?

Through specialized sensory structures in the inner ear that detect changes in position.

What is the primary reproductive output strategy of capelin?

They graze on plankton and use semelparity for reproduction.

What is the primary function of hair cells in the fish inner ear?

They convert mechanical stimuli into neural signals for balance and orientation.

What adaptations do fish have for orienting in a gravitational field?

They have specialized endorgans like otoliths and hair cells that respond to gravity.

What is loss of equilibrium in fish?

The inability of fish to maintain an upright position within the water column.

Define immobility in fish.

The inability of fish to move or swim unless prodded.

What are some abnormalities observed in fish?

Lethargy, hyperactivity, change in respiration, color change, tremors, spasms, bloated abdomens, and position loss in the water column.

What are upside-down catfishes known for?

They feed and swim inverted but show no change in the peripheral organization of the vestibular system.

What is unique about flatfishes?

One eye migrates across the head so one side lies flat, allowing them to swim on the bottom.

What is the role of the vestibular system in upside-down catfishes?

There is no change in the vestibular system, but the utricle is replaced by the saccule.

What is the significance of the 'head-stander' tetras?

Some species tilt their head upward or downward by as much as 30°; the penguin fish has a modified utricular otolith organ.

What is the lateral line system in fish?

A mechanosensory system that detects hydrodynamic and physical environmental cues.

How do fish use their lateral line system?

To perceive water movements of both biotic and abiotic origin and guide behavior.

What are the eight trunk canal patterns present in teleosts?

Complete straight, interrupted, multiple, complete arched, incomplete, complete dorsal, absent, and complete ventral.

What are the four head canal system designs known in teleosts?

Narrow, simple canal system; reduced canal system; widened canal system; branched canal system.

What is the function of canal receptors in the lateral line system?

They detect velocity and angular momentum of fluid moving inside ridged canals.

What is the mode of detection for lateral line endorgans?

Cupular displacement resulting from frictional drag.

What is Svenning in fish behavior?

The maintenance of school structure sensed primarily in the posterior or trunk region.

What happens when the lateral line nerve is cut in fish?

Many fish are unable to maintain adequate school structure.

How do fish detect local disturbances?

Through the lateral line system, which captures local hydrodynamic interactions.

What is the impact of severing the Bluegill lateral line?

The sunfish lose homing ability and the ability to school effectively.

How do predators use the lateral line system?

To accurately localize prey, supplementing information with vision or chemoreception.

How do prey fish utilize the lateral line system?

To detect imminent capture and target safely away from predators.

What is the response of sculpin to vibrations?

They will turn to snap at a vibrating ball as though it were food.

What adaptation do blind fishes have regarding the lateral line system?

They have especially precise lateral line senses that allow navigation and obstacle avoidance.

Fish

Aquatic vertebrates that have gills, fins, and typically scales.

Respiration

The process of gas exchange; for fish, primarily involves taking in oxygen and expelling carbon dioxide.

Gills

Respiratory organs in fish that allow for gas exchange with water.

Hypercarbia

An increase in carbon dioxide levels in the bloodstream.

Acid-base regulation

The mechanism by which organisms maintain stable pH levels in their body fluids.

Ventilation

The process of moving water over gills for gas exchange.

Gill morphology

The structural characteristics of gills, including shape and arrangement.

Elasmobranch

A class of fish that includes sharks and rays, characterized by having cartilage rather than bones.

Counter-current exchange

A mechanism that maximizes oxygen uptake in gills by flowing water and blood in opposite directions.

Branchial

Relating to the gills.