Chapter 24: Fishes, Osteichthyes, Class: Sarcopterygii

Question 1

Lung Fishes:

-Australian lungfishes rely on what that their close relatives do not?

Answer 1

• gill respiration since

Question 2

South American and African Lung fishes are different from Australian lungfishes in what way?

Answer 2

• they can live out of water for long periods of time

Question 3

When did Rhipidistians flourish and when did they go extinct?

Answer 3

• Late Paleozoic

- after that they became extinct

Question 4

The Coelacanth:

• Arose in what time period, peaked when?
• Living Coelacanth are descendants of what?
• They have a Diphycercal tail, meaning what?
• Describe their young?

Answer 4

• Devonian, Mesozoic than dramatically declined
• Devonian freshwater stock
• small lobe between the upper and lower caudal lobes
• young are born fully formed after hatching from eggs.

Question 5

Most fishes swim maximally at __ body lengths per second but larger fish therefore swim __ than smaller ones.

Answer 5

• ten

- faster

Question 6

The __ and __ musculature propels a fish. Muscles are arranged in zigzag bands called what?

Answer 6

• trunk and tail
• myomeres
  L> shape of W on the side of fish, internally the bands are folded and nested, each myomere pulls on several vertebrae.

Question 7

Fishes are slightly heavier than water. To keep from sinking, a shark must do what?

Answer 7

• continually move forward fins keeping them angled up

Question 8

Sharks liver has a special fatty hydrocarbon also called what? Whats its function?

Answer 8

• Squaline

- acts to keep the shark buoyant

Question 9

What is a swim bladder and its function?

Answer 9

• gas filled space, the most efficient flotation device

Question 10

What did the swim bladder arise from?

• What organism are they absent in?
• How does the fish control depth?
• How does the fish counteract pressure as it descends?
• Ascends?

Answer 10

• Tunas, abyssal fishes and most bottom dwellers
• via adjusting volume of gas in swim bladder
• the bladder is compressed making the total density of the fish greater
• the bladder expands making the fish lighter and it will rise faster

Question 11

What two ways is gas removed?

• Primitive Physostomous
• Advanced Teleosts are physoclistous

Answer 11

• Pneumatic duct connecting swim bladder and esophagus

- Pneumatic duct is lost and gas must be secreted into the blood from a vascularized area.

Question 12

Both types of gas removal require gas to be secreted into what?

Answer 12

• the bladder from the blood via gas gland

Question 13

What makes up the countercurrent exchange system used to trap gases.

Answer 13

• network of capillaries and rete mirabile

Question 14

Gas glands secrete what?

Answer 14

• lactic acid that forces hemoglobin to release its load of oxygen

Question 15

Describe rete capillaries! Deep fish vs surface dwelling

Answer 15

• short in surface- dwelling fish and very long in deep sea fishes

Question 16

A few shallow water inhabiting physostomes do what to fill their swim bladder?

Answer 16

• gulp air to fill the swim bladder

Question 17

• Fish gills are ___ with thin epidermal membranes folded into plate like ___.
• Gills are inside the __ cavity and covered with a movable flap called the ___.

Answer 17

• filaments
• pharyngeal
• operculum

Question 18

What does the operculum do?

Answer 18

• protects delicate gill filaments and streamlines body
• pumping action by this helps move water through gills
• water flow over the gills is continuous

Question 19

Water flow is ___ to blood flow.

Answer 19

• opposite

- countercurrent exchange maximises exchange of gases

Question 20

What is ram ventilation? (used by active fishes)

Answer 20

• forward movement is sufficient to force water across gills

- such fishes are asphyxiated in restrictive aquarium even if the water is saturated with oxygen.

Question 21

Freshwater is ___ to fish blood. Water enters the body and __ is lost by diffusion. Scaled and mucous covered body is mostly ___, but gills allow water and salt __.

Answer 21

• hypotonic (less of a concentration)
• salt
• permeable
• fluxes

Question 22

Freshwater fishes are ___ regulators. The ____ pumps excess water out. Special salt absorbing cells located in the ____ actively move salt ions from water into fishes blood. They devote ___ energy to maintaining osmotic balance.

Answer 22

• hyperosmotic
• Opisthonephric kidney
• epithelium
• little

Question 23

Euryhaline fishes live where?

Answer 23

• estuaries where salinity fluctuates throughout thee day

Question 24

Marine bony fishes are ___ regulators.

Answer 24

• hypoosmotic
• blood is hypotonic to seawater
• tend to lose water and gain salt and risk drying out.