lecture 6

Question 1

what characteristics of the living hagfishes and lampreys suggest that their lineages arose very early in vertebrate evolution?

Answer 1

Hagfishes lack bone, paired fins, and scales in their skin. Hagfishes have neither a cranium nor vertebral column.

Lampreys have only rudimentary traces of vertebrae.

These observations suggest that their lineages arose before these structures appeared in vertebrates

Question 2

what traits in conodonts and ostracoderms are derived (more advanced) relative to those in hagfishes and lampreys?

Answer 2

structures made of bone or bone-like material and, in some ostracoderms, a brain sub-divided into 3 regions

Question 3

why was the evolution of jaws so important for the evolution of vertebrates? 4

Answer 3

1. increased flexibility and efficiency
2. increased diversity of diet
3. more food= bigger individuals
4. moveable fins increased agility in movements

Question 4

how do the air bladder and fins of Actinopterygii increase their locomotor abilities?2

Answer 4

1. allowing them to rise or sink easily in the water column.

2. Their fin rays allow them to engage in precise movements during locomotion

Question 5

what characteristics do bony fishes possess that make them so competitive? 5

Answer 5

1. strong light bones
2. moveable fins
3. scales and mucus (=streamlining and anit-bacterial)
4. swim bladder (=improved buoyancy control)
5. operculum (=improved breathing)

Question 6

what characteristics of sharks make them more efficient predators than the acanthodians or placoderm? 4

Answer 6

1. well developed sensory system to detect prey
2. lightweight skeleton and absence of a heavy body armor allow them to ursue prey rapidly
3. numerous teeth that are replaced when damaged or worn
4. loosely attached jaws that permit them to suck in large chunks of food

Question 7

How do the lungs of lungfishes allow them to survive in stressful environments?

Answer 7

allow them to survive in environments with low oxygen content because they can acquire oxygen from the air

Question 8

Ghathostomata includes the evolution of 2 things?

Answer 8

1. hinged jaws

2. movable fins

Question 9

common name for myxinoidea

Answer 9

hagfish

Question 10

petromyzontoidea common name

Answer 10

lampreys

Question 11

which agnathan hasnt got a specialised structure around the dorsal nerve cord? (no rudimentary vertebrae)

Answer 11

myxinoidea -hagfishes

Question 12

which agnathan has an oral disk

Answer 12

petromyzontoidea-lampreys

Question 13

Condonts (cone tooth) :

2 identifying features (rest are in the phylogeny tree)

Answer 13

1. movable eyes

2. bone/bone-like tissue: bone-like feeding structures made of dentine

Question 14

2 characteristic of ostracoderms

Answer 14

1. armored skin with bony plates and scales

2. no true vertebral column or fins

Question 15

jaws evolved from…..

Answer 15

gill arches in the pharynx of jawless ancestor.

• one pair of ancestral gill arches formed bones in the upper and lower jaws
• 2nd pair attached the jaws to the cranium

Question 16

4 functions of movable fins

Answer 16

1. stability (e.g. dorsal fin and anal fin)
2. steering (paired pectoral fins as well as paired pelvic fins)
3. power and trust (e.g. caudal fin)
4. deters predators

Question 17

4 reasons why the development of the jaws and fins were so NB

Answer 17

1. increased flexibility and strength
2. increased diversity of diet
3. more food= bigger individuals
4. moveable fins increased agility in movement

Question 18

3 characteristics of placoderms (could compare them with acanthodii= same characteristics are very different)

Answer 18

1. covered by heavy bony plates & scales
2. no separate teeth
3. fins with internal skeletal support and muscle

Question 19

3 characteristics of acanthodii (spiny sharks)

Answer 19

1. smell, light scales, streamline bodies
2. well developed eyes, large jaws and numerous teeth
3. ventral spines and fins with internal skeletal support

Question 20

chrondrichthyes are referred to as …branchs

Answer 20

elasmobranches

Question 21

elasmobranchs (chondrichthyes )include 3 species

Answer 21

1. skates
2. rays
3. sharks

Question 22

skates and rays are both

Answer 22

dorsoventrally-flattened bottom dwellers

Question 23

sharks 6 characteristics

Answer 23

1. streamlined
2. dominant predators
3. flexible fins but not movable
4. lightweight skeleton
5. buoyant livers
6. no gill cover- breathing=less efficient

Question 24

Elasmobranch feeding adaptations 2

Answer 24

1. teeth develop in spirals(new teeth migrate forward as old break off)
2. digestive system modified to incr time food stays in digestive system and SA for absorption

Question 25

Definition of olfaction

Answer 25

the sense of smell

Question 26

elasmobranch sensory systems are composed of 4 things

Answer 26

1, vision 2. olfaction - smell 3. electroreceptors 4. lateral-line system

Question 27

what is the function of the electroreceptors of elasmobranch

Answer 27

to detect weak electric currents produced by prey

Question 28

what is it and the function of the lateral-line system of elasmobranch

Answer 28

It is a row of tiny sensors in canals along both sides of the body function = detects vibrations in the water

Question 29

elasmobranch undergo internal/external fertilisation

Answer 29

internal

Question 30

the embryos of elasmobranch are nourished in 3 ways

Answer 30

1. produce large yolky eggs with tough leathery shells 2. retain eggs within the oviduct until young hatch 3. nourish young within a uterus

Question 31

2 lineages of bony fishes

Answer 31

1. actinopterygii-ray-finned fishes | 2. sarcopterygii-fleshy-finned fishes

Question 32

actinopterygii have fins supported by?

Answer 32

thin, flexible bony rays

Question 33

sarcopterygii have fins supported by.....2

Answer 33

1. muscles | 2. internal bony skeleton

Question 34

actinopterygii branch to form

Answer 34

teleosts e.g. seahorses

Question 35

2 NB structures in teleost

Answer 35

1. operculum | 2. swim bladder

Question 36

difference between reproduction of teleost reproduction in marine fishes vs freshwater fish

Answer 36

Marine= produce planktonic larvae-eggs fertilised and hatch in water Freshwater= direct development - eggs hatch into baby fish or sometimes gives birth to live young (frequently parental care)

Question 37

sarcopterygii species lobe-finned fishes example

Answer 37

- 2 species of the coelacanths in Indian ocean

Question 38

sarcoptrygii have 2 species

Answer 38

1. lobed-finned fish | 2. lungfishes

Question 39

NB adaptation lungfish have

Answer 39

primitive lungs supplement/ replace breathing with gills