Osteichtyhes

Question 1

what is the name for bony fishes, how is it spelt

Answer 1

Osteichthyes

Question 2

featires of Osteichthyes

Answer 2

• over 30,000 species
• over 95% of all fish
• First fossils approx. 400 MYA
• Radiated in the Devonian into 2 main groups

Question 3

What are the two main group of Osteichthyes

Answer 3

1) Actinopterygii (ray-finned)

2) Sarcopterygii (lobe-finned)

Question 4

What infra-class are the vast majority of Actinopterygii

Answer 4

Teleost - typically characterised by presence of a homocercal tail, a tail in which the upper and lower halves are about equal.

• make up most of Actinopterygii,

Question 5

Example of a non-teleost + features

Answer 5

E.G. Sturgeon

• Cartilagenous skeleton
• Swim bladder
• Pertrudable jaw
• Lost many scales on body, instead have “scutes” - bony structures on the surface
• endangered -> used in caviar industry

Question 6

second example of a non-teleost

Answer 6

E.g. paddlefish

• has a “paddle” detector that is sensitive to electrical impulses

Question 7

General features of teleosts

Answer 7

• Highly developed fishes, incredible variety over the different groups
• Body covered by dermal scales (in some groups scales are absent)
• Caudal fin is homoveral type, pelvic fins are situated towards anterior end of body
• Endoskeleton completely bony in nature
• swim bladder present in most fishes

Question 8

Caudal
homoveral
buccal

Answer 8

• at or like a tail (end of body)
• having the upper and lower lobes approximately symmetrical and the vertebral column ending at or near the middle of the base.

Question 9

How are telosts feeding mechanisms specialised

Answer 9

• Flexibility of bones of skulls + jaws , exploit rnage of prey
• Jaws -> suction device increased colume of buccal cavity
• e.g. accessory jaws in the Moray ell come out of its mouth to grab and pull prey, ( lives in crevices so cant use suction, jaw is an adaptation)

Question 10

Respiration in Bony-fishes

Answer 10

1) gills, mouth has a pump which pushes water over the gills

2) Ram ventilation
- no pumping ventilation mechanism
- swim with their mouths constantly open (have to stay active)
- some can switch this on for period of high movement

Question 11

features of eels (teleost’s)

Answer 11

• reduced fins (live in crevices)
• lost pelvic fins ( or very tiny)
• undergo huge migrations when they spawn
• catadomous , live in fresh water spawn in marine water

Question 12

What are the 3 groups of lobe-finned fishes (sarcopterygii)

Answer 12

1) lungfishes (3 genera)
2) coelacanths (living fossils)
3) those that gave rise to tetrapods

Question 13

Sarcopterygii

Answer 13

1) Lobe finned fishes
are bony fish with fleshy-, lobed-paired fins, which are joined to the body by a single bone . These fins evolved into legs of the first tetrapod land vertebrates, amphibians.

Question 14

Lungfishes

Answer 14

1) Australian - has well developed fins + scales,
- lives in permanent water bodies + has working gills
2) African - live in temporary water bodies , use reduced pelvic fins for moving on ground , uses lungs to breathe . In dry season burrow into bottom mud and cover themselves in mucus.
3) South American - little is known about them , use lungs to breed

Question 15

Coelacanths

Answer 15

• though to have gone extinct 80 MYA

- discovered in 1938 by Majorie Courtenay-Latimer