Invertebrate Chordates

Question 1

Give the bigger group to which the invertebrate chordates belong.

Answer 1

The chordates

Question 2

Give the 2 sub groups of the IC ?

Answer 2

Urochordata

Cephalochordata

Question 3

What groups are found within the Urochordata ?

Answer 3

Ascidiacea
Thaliacea
Appendicularia

Question 4

What groups are found within the Cephalochordata ?

Answer 4

Branchiostoma,

Amphioxus

Question 5

What species are found within the Ascideacea ?

Answer 5

Sea squirts and tunicates

They live in colonies

Question 6

Do Ascideacea have a Lophophore ?

Answer 6

No, they pump water in and out using cilia

Question 7

Describe the journey of water through Ascideacea ?

Answer 7

Water enters through the oral siphon and exits through the atrial siphon

Question 8

What is the purpose of the pharyngeal baskets ?

Answer 8

They filter water for nutrients as are rich in iodide.

These nutrients then diffyse into the stomach

Question 9

Describe the Fertilisation of Ascideacea.

Answer 9

External fertilisation

Hermaphrodites (M and F)

Question 10

How do Ascideacea prevent other organisms landing on them ?

Answer 10

Surrounded by a velvety sac.

Question 11

Describe the living habits of Thaliaceae.

Answer 11

Solitary or Colonial

Question 12

What is a Pyrosoma ?

Answer 12

Tube structure,
Pumps water into a larger structure
Can emit light to scare predators

Question 13

Do thaliaceae have a nervous system ?

Answer 13

No,

But have physical co-ordination systems which generate motion.

Question 14

What is the main species in the group thaliaceae ?

Answer 14

Salps

Question 15

Describe the larvae of the Ascideacea.

Answer 15

Adhesive papillae- attachment to substrate

Tail- enables movement via caudal muscles

Notochord- generates wave of activity to activate muscles

Question 16

What is the main species found in the group Appendicularia ?

Answer 16

Larvaceans

Question 17

Give an adaption of the larvaceans which enables them to filter feed.

Answer 17

Secretion of a mucus house outside body every 3 hours.

Beating their tail also encourages movement of water through filter

Question 18

Give the main species found in the Cephalochordata.

Answer 18

Branchiostoma

Question 19

What do Branchiostoma look similar to ?

Answer 19

Fish larvae

Question 20

What do Branchiostoma have instead of a pharyngeal basket ?

Answer 20

A pharynx with gill slits, modification of the basket

Question 21

Give a benefit of the branchiostomes elongated body.

Answer 21

Enables longer digestive system.

Question 22

Give some key morphological adaptions of the branchiostome.

Answer 22

Caudal fin (post-anal)
Myotomes- muscle
Notochord- co-ordination of movement
Endostyle- secretes muscus to aid transportation of food

Question 23

Describe the head of the brachistome, which has undergone cephalisation

Answer 23

Anterior brain

Pharyngeal slits- increasing efficiency of oxygen harvesting

Cartilaginous rods with blood vessels inside- ^ efficiency

Heart

Question 24

Increased efficiency of oxygen harvesting enables….

Answer 24

More powerful muscles, which means rapid movement,

Question 25

Give the 5 key parts of a chordate body plan.

Answer 25

``` Notochord Dorsal hollow nerve chord Digestive system Muscular post anal tail Pharyngeal slits ```

Question 26

What does the dorsal nerve chord develop from in chordates ?

Answer 26

``` The plate of the ectoderm, creating a hollow tube above the notochord. Becomes CNS (Brain and spine) ```

Question 27

What happens to these 5 key parts of the chordate body plan as the organism develops ?

Answer 27

Many features will disappear as the organism develops, but are ALL present at embryonic level.

Question 28

Why is the development of the notochord so important ?

Answer 28

It enables muscles to attach Gives skeletal support Gives capacity to modify body shape.

Question 29

Give the 2 subphylum of the invertebrate chordates.

Answer 29

Cephalochordates | Urochordates (tunicates)

Question 30

Why are these 2 groups found within the invertebrate phylum ?

Answer 30

Species lack a head and vertebrae. | Use pharyngeal slits for filter feeding not respiration.