Chordate Basics

Question 1

What are the 5 basic chordate characteristics?

Answer 1

perforated pharynx / pharyngeal gill slits

notochord

dorsal, hollow nerve cord

endostyle/thyroid

post-anal, muscular tail

Question 2

T or F: every chordate, at every stage, has all 5 characteristics

Answer 2

false

the 5 characteristics are present at any life stage of all chordates

Question 3

Describe perforated pharynx/pharyngeal gill slits

Answer 3

slits/holes in pharynx (posterior to mouth)

Question 4

What is the major function of a perforated pharynx?

Answer 4

to allow water that has entered the animal’s mouth to leave without passing through the digestive tract

Question 5

How is a perforated pharynx used in chordates?

Answer 5

for suspension-feeding

Question 6

For what functions have perforated pharynxes been modified?

Answer 6

gas exchange (aquatic vertebrates, ex. fish)
jaw support
hearing

Question 7

Describe the notochord

Answer 7

a skeletal structure between the digestive tube and nerve cord

elastic, laterally flexible, but composed of pretty stiff tissues

Question 8

In vertebrates, which life stage is the notochord often present?

Answer 8

embryo

Question 9

What does the notochord become in vertebrate adults?

Answer 9

remnants - ex. vertebral disks

Question 10

Where is the dorsal, hollow nerve cord located?

Answer 10

dorsal to the notochord

Question 11

What does the dorsal, hollow nerve cord develop from? develop into?

Answer 11

from: ectoderm

into: brain and spinal cord

Question 12

What is the muscular, post-anal tail made of? what does it do?

Answer 12

made of muscular and skeletal elements

used for propulsion in aquatic animals

Question 13

What is the endostyle/thyroid gland?

Answer 13

a ciliated groove in the floor of the pharynx used to trap food particles

thyroid glands metabolize iodine

Question 14

What are the 2 invertebrate groups of Chordates?

Answer 14

Cephalochordata (lancelets/amphioxus)

Urochordata (Tunicates)

Question 15

Which is the major genus of Cephalochordates?

Answer 15

Branchiostoma

Question 16

What are two other names for Cephalochordates?

Answer 16

lancelets
amphioxus

Question 17

What are the basic characteristics of Cephalochordates (lancelets)?

Answer 17

small
blade-like
retain chordate characteristics into adulthood

Question 18

T or F: lancelets are the only chordates that retain chordate characteristics into adulthood

Answer 18

true

Question 19

Compare the larval stage and adult stage of Cephalochordates (lancelets)

Answer 19

larvae: planktonic, feeding

adults: can swim, but mostly burrow

Question 20

How do Cephalochordates (lancelets) conduct gas exchange?

Answer 20

across external body surface

Question 21

What function do pharyngeal gill slits have in Cephalochordates (lancelets)?

Answer 21

used for filter-feeding

Question 22

Describe Urochordates (Tunicates)

Answer 22

small
marine
sessile
suspension feeding
solitary or colonial

Question 23

What are the distinguishing features of Urochordates (tunicates)?

Answer 23

body is fully enclosed in a tunic (composed of tunicin and other proteins)
U-shaped gut
endostyle present
ganglion nervous system
tubular heart can reverse direction of blood flow

Question 24

What class do most tunicates belong to?

Answer 24

Ascidiacea

Question 25

What type of chordate can reverse its blood flow?

Answer 25

Urochordates (Tunicates)

Question 26

Compare the larval stage and adult stage of Urochordates (Tunicates)

Answer 26

larvae: tadpole short-lived non-feeding tail with notochord and dorsal hollow nerve cord adults: no notochord, nerve cord, or tail

Question 27

Describe reproduction in Urochordates (tunicates)

Answer 27

individuals are hermaphroditic (one ovary, one testis) reproduce tadpole larva

Question 28

T or F: adult Urochordates (tunicates) look very similar to larvae and retain many of the chordate characteristics

Answer 28

false they look very different and have lost the tail, nerve cord, and notochord retain pharyngeal slits for filter feeding

Question 29

Which of the basic chordate features do humans retain as an adult? which are modified?

Answer 29

lost: post-anal tail retained: endostyle = thyroid nerve cord = brain and spine notochord = vertebral disks gill slits = jaws, ear bones

Question 30

What are the major advantages for paired pharyngeal gill slits?

Answer 30

allows filter feeding - not everything sucked into the mouth goes through the digestive tract allows external gas exchange

Question 31

What are the major advantages for brain and dorsal nerve cord?

Answer 31

to sense and navigate and respond to environment

Question 32

What are the major advantages for segmented muscles?

Answer 32

for movement to catch prey and avoid predators to navigate environment

Question 33

What are the major advantages for the notochord?

Answer 33

structural support

Question 34

What are the major advantages for post-anal tail?

Answer 34

for movement, especially if aquatic, to use as a propulsive force for balance on land

Question 35

What are the major advantages for endostyle or thyroid?

Answer 35

endostyle assists in filter feeding thyroid assists in iodine metabolism