Lecture 6

Question 1

What are the 5 features of osteichthyes?

Answer 1

Dermal bones, jaws, pectoral girdle, branchiostegial rays and gas bladders

Question 2

On what part is the unique pattern of the jaws and braincase that is carried through to tetrapods?

Answer 2

Dermal bones

Question 3

What are the maxila, premaxilla and dentary?

Answer 3

Maxilla/premaxilla: upper jaw & dentary: lower jaw

Question 4

What does the extension of the dermal bones to the girdle form?

Answer 4

The operculum that covers the gills

Question 5

What is the function of the branchiostegial rays?

Answer 5

They help expand the mouth

Question 6

What is the Devonian period known as?

Answer 6

The age of the fishes

Question 7

What did the first bony fishes resemble?

Answer 7

Acanthodians (spiny sharks)

Question 8

What are sarcopterygians?

Answer 8

Lobe-finned fish

Question 9

Describe the limbs of sarcopterygians

Answer 9

The rays of paired fins extended from the central shaft of the bones to support the fin web. Muscles on outside of the body wall

Question 10

What is the name given to modern day bony fishes?

Answer 10

Teleosts

Question 11

Describe the evolution of the mouth of Dipnoi (lungfish)

Answer 11

Tooth-bearing bones were lost, palatoquadrates fused to cranium, teeth scattered over palate & fused into ridges along lateral margins

Question 12

Describe the evolution of the fins/bones of Dipnoi

Answer 12

Dorsal, caudal & anal fins merged into one, caudal fin became symmetrical. Skull bones went from many small to few large

Question 13

True or false? Most fish are denser than water

Answer 13

True

Question 14

Describe the embryonic development of the swim bladder

Answer 14

Outpocketings of the dorsal or ventral side of

the gut in the pharyngeal region

Question 15

How do fish increase the surface area of the lungs?

Answer 15

Elaborating the walls (an alveolar lung) or by adding a second lobe

Question 16

What do African Lungfish do during dry/summer months?

Answer 16

Aestivate, a period of dormancy to wait out the harsh conditions

Question 17

What happens during an African Lungfishes aestivation?

Answer 17

They create a mucous-lined burrow with breathing holes. Metabolism and respiratory demands drop and muscle proteins are used as an energy source

Question 18

What enamel-like element do stem actinopterygians have?

Answer 18

They have ganoine, unlike sarcopterygians which have cosmine

Question 19

When did major morphological changes occur in time?

Answer 19

Towards the end of the Palaeozoic period

Question 20

Name a few of the morphological changes that occurred towards the end of the palaeozoic period

Answer 20

Caudal fin lobes were nearly symmetrical, fewer rays in fins which increased flexibility and reduced dermal armour, supporting more versatile locomotion

Question 21

When did the new lineage of Neopterygians emerge?

Answer 21

In the Permian period

Question 22

Describe the jaws before and after the permian era

Answer 22

Cheek bones allowed little opening of the orobranchial chamber. After, short maxilla freed the cheek at posterior end.

Question 23

What did the freeing of the cheek enable fish to do?

Answer 23

Swing out large mouth and increase suction

Question 24

What enables sturgeons to respire when feeding?

Answer 24

A permanent opening at the top of the operculum for inflow, the spiracle isn’t used as much.

Question 25

What is the long rostrum on the paddlefish innverated for?

Answer 25

It has ampullary organs to detect electric fields

Question 26

What do gars and bowfins share?

Answer 26

The dorsal gas bladder that is vascularised and has a respiratory and buoyancy role. Heavy scaling too

Question 27

What two things does the Weberian system connect?

Answer 27

Connects the swim bladder to the auditory system in fish

Question 28

Describe the function of the Weberian system?

Answer 28

Sound vibrates the swim bladder, tripus (bone) pivots on the vertebra. Motion is transmitted by ligaments to the intercalarium and scaphum. Movement of scaphum compresses membranous labyrinth

Question 29

What is the membranous labyrinth?

Answer 29

The inner ear

Question 30

What are the two elements that receives the transmitted sound from the ligaments?

Answer 30

The intercalarium and the scaphum