ch4 1

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Bony fishes are neutrally ______ (i.e., have the same density as water).

buoyant

In countercurrent exchange, blood cells are separated from oxygen-rich water only by the thin ______ cells of the capillary wall.

epithelial

Countercurrent flow maintains a ______ in oxygen concentration between blood and water for the full length of the lamella.

difference

If water and blood flowed in the same direction, the ______ in oxygen concentration and the diffusion gradient would be high initially.

difference Signup and view all the answers

In figure 4-2, the direction of ______ flow across the gill opposes the flow of blood through the secondary lamellae.

water Signup and view all the answers

Blood leaving the gill has a high ______ concentration due to countercurrent exchange.

oxygen Signup and view all the answers

These fishes do not have to swim to maintain their vertical position in the ______ column.

water Signup and view all the answers

The only movement they make when at rest is backpedaling of the ______ fins to counteract the forward thrust.

pectoral Signup and view all the answers

Fishes capable of hovering in the water like this usually have well-developed ______ bladders.

swim Signup and view all the answers

The ______ bladder is located between the peritoneal cavity and the vertebral column.

swim Signup and view all the answers

The swim bladder wall, which has smooth walls composed of interwoven ______ fibers without blood vessels, is virtually impermeable to gas.

collagen Signup and view all the answers

Neutral buoyancy produced by a swim bladder works as long as a fish remains at one ______, but if a fish swims vertically up or down, the hydrostatic pressure that the surrounding water exerts on the bladder changes.

depth Signup and view all the answers

The rete mirabile is a structure that moves gas, especially ______, from the blood to the gas bladder.

oxygen Signup and view all the answers

The gas gland secretes oxygen by releasing ______ acid and carbon dioxide.

lactic Signup and view all the answers

Acidiﬁcation causes ______ to release oxygen into solution.

hemoglobin Signup and view all the answers

The gas gland is located ______ the gas gland.

underlying Signup and view all the answers

The rete mirabile is a structure that is known as a ______ net.

wonderful Signup and view all the answers

Gas secretion occurs in many deep-sea ﬁshes despite the hundreds of ______ of gas pressure within the bladder.

atmospheres Signup and view all the answers

Fishes that migrate over large vertical distances depend more on lipids such as ______ esters than on gas for buoyancy.

wax Signup and view all the answers

Air-Breathing Divers Air in the lungs of air-breathing aquatic vertebrates reduces their ______.

density Signup and view all the answers

Deep-diving animals, such as elephant seals and some whales and porpoises, face a different problem, however. These animals dive to depths of ______ meters or more.

1000 Signup and view all the answers

Under those conditions, nitrogen would be forced from the air in the lungs into solution in the ______ and carried to the tissues at high pressure.

blood Signup and view all the answers

Specialized diving mammals avoid the problem by allowing the ______ cavity to collapse as external pressure rises.

thoracic Signup and view all the answers

Air is forced out of the lungs as they collapse, reducing the amount of nitrogen that ______ into the blood.

diffuses Signup and view all the answers

Aquatic mammals such as whales and porpoises have spherical lenses like those of ______

fishes Signup and view all the answers

Fishes have taste-bud organs in the mouth and around the head and anterior ______

fins Signup and view all the answers

Sharks and salmon can detect odors at concentrations of less than 1 part per ______

billion Signup and view all the answers

Homeward-migrating salmon are directed to their stream of origin from astonishing distances by a chemical signature from the home stream that was permanently imprinted when they were ______

juveniles Signup and view all the answers

Mechanical receptors detect ______, sound, pressure, and motion

touch Signup and view all the answers

Fishes also have ______ detectors at the base of the semicircular canals that allow them to distinguish up from down

gravity Signup and view all the answers

What property of seawater makes it possible for sharks to detect the electrical activity of their prey?

high conductivity Signup and view all the answers

Where are the ampullae of Lorenzini located in sharks and rays?

on their heads in sharks and on the pectoral fins in rays Signup and view all the answers

What is the function of the canal in the ampullae of Lorenzini?

to detect differences in electrical potential between the tissue and the distant pore opening Signup and view all the answers

What is the threshold of detection for electroreceptors in sharks?

lower than 0.01 microvolt per centimeter Signup and view all the answers

What type of activity generates electrical potential in animals?

muscle activity Signup and view all the answers

What is the function of electroreceptors in sharks?

to detect prey Signup and view all the answers

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

The cupula is a gel-like substance that covers the sensory hair cells in the lateral line organ. It stimulates the hair cells through deflection, which leads to changes in the nerve discharge rate, allowing the fish to detect water currents and directional information. Signup and view all the answers

How does the deflection of the kinocilium in one direction versus the opposite direction affect the hair cell receptor potential?

Deflection of the kinocilium in one direction depolarizes the cell, increasing the discharge rate (excitation), while deflection in the opposite direction hyperpolarizes the cell, decreasing the discharge rate (inhibition). Signup and view all the answers

What is the effect of cupula displacement on the afferent nerve discharge rates in a lateral line organ?

Cupula displacement increases the firing rate in one afferent nerve and decreases it in the other nerve, signaling the direction of water currents on different surfaces of the fish's body. Signup and view all the answers

How do the paired hair cells in a neuromast organ respond to cupula displacement?

Each pair of hair cells signals the direction of cupula displacement, with one cell being excited and the other inhibited, allowing the fish to detect the direction of water currents. Signup and view all the answers

What is the role of the neuromast organ in the lateral line system of fish?

The neuromast organ detects water currents and vibrations, allowing the fish to detect predator or prey movements, navigate, and maintain its position in the water column. Signup and view all the answers

How do the lateral line organs in fish contribute to their spatial awareness and navigation?

The lateral line organs provide information about water currents, vibrations, and directional information, allowing the fish to navigate, detect prey or predators, and maintain its position in the water column. Signup and view all the answers

What do sharks use for navigation and locating prey?

electroreception Signup and view all the answers

What do sharks detect in their surroundings using electroreception?

electrical activity Signup and view all the answers

What is the role of the electromagnetic field at Earth's surface in shark navigation?

produces tiny voltage gradients Signup and view all the answers

What is the function of the experiment shown in Figure 4-8?

to demonstrate the electrolocation capacity of sharks Signup and view all the answers

What is the relationship between electrical signals and olfactory cues in shark prey detection?

sharks use electrical signals when available, and olfactory cues when electrical signals are absent Signup and view all the answers

What is the significance of the agar shield in the experiment shown in Figure 4-8?

blocks olfactory cues but allows electrical signals to pass Signup and view all the answers

What is the purpose of the dual system in sharks, and how does it enable them to find food items?

The dual system allows sharks to find both living and dead food items by using electrical and olfactory cues. Signup and view all the answers

How do weakly electric teleost fishes produce their electric discharge, and what is the range of pulse rates observed in these fishes?

Weakly electric teleost fishes produce a pulsating discharge, with pulse rates ranging from 50 to 300 cycles per second, but knife fishes can reach up to 1700 cycles per second. Signup and view all the answers

How do electric fishes detect the presence, position, and movement of objects in their environment?

Electric fishes detect objects by sensing the distortions of their electric field caused by the presence of electrically conductive and resistive objects. Signup and view all the answers

What is the role of rocks and other objects in the environment of electric fishes, and how do they affect the fish's electric field?

Rocks are highly resistive, while other fishes, invertebrates, and plants are conductive, and these objects distort the electric field of the fish, allowing it to detect their presence and position. Signup and view all the answers

What is the advantage of having a pulsating electric discharge, and how does it relate to the energy costs of maintaining an electric field?

The pulsating electric discharge reduces the energy costs of maintaining an electric field, allowing the fish to conserve energy while still detecting objects in its environment. Signup and view all the answers

How do the electric fields of weakly electric fishes interact with their environment, and what is the significance of the electric field's range?

The electric field of weakly electric fishes extends outward for a considerable distance in freshwater, and its range is significant because it allows the fish to detect objects at a distance. Signup and view all the answers

What is the primary function of electroreceptors in weakly electric fishes?

To detect the presence of nearby objects by sensing distortion of the lines of electrical force. Signup and view all the answers

How do conductive objects affect the electric field of a weakly electric fish?

They concentrate the field on the skin of the fish. Signup and view all the answers

What happens when two weakly electric fishes swim close to each other?

They change the frequencies of their discharges. Signup and view all the answers

What is the likely origin of electroreception in vertebrates?

An early feature of vertebrate evolution. Signup and view all the answers

What type of cells have a prominent kinocilium and fire when the environment around the kinocilium is negative relative to the cell?

Electroreceptor cells. Signup and view all the answers

What is the location of the electroreceptor cells in the brain?

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