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Flashcards in Chordate Lecture Deck (39)
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1

Chordata shared ancestral characteristics

bilateral symmetry, metamerism, coelom, anteroposterior axis, cephalization

2

Chordate Synapomorphies

notochord, single dorsal tubular nerve cord, pharyngeal slits/pouches, endostyle, postnatal tail

3

notochord is?

a flexible rod-like structure

4

notochord position?

ventral to nerve cord

5

notochord function?

locomotion --> skeletal axis for muscle attachment to facilitate undulatory movement

6

notochord appearance in the embryo?

as first part of the endoskeleton

7

notochord persists after embryo?

in protochordates (some) and jawless vertebrates

8

notochord replaced by?

cartilaginous or bony vertebrae in jawed vertebrates

9

nerve cord initially?

hollow tube but mostly fills in during development in most taxa

10

nerve cord produced by?

infolding of dorsal cells

11

anterior end of nerve cord?

in vertebrates, becomes brain

12

pharyngeal groove formation?

inpocketing of ectoderm

13

pharyngeal pouch formation?

outpocketing of adjacent endodermal lining of pharynx

14

pharyngeal slit formation?

fusion of inpockets and outpockets (aquatic chordates)

15

pharyngeal pouches produce?

middel ear cavity, Eustachian tube, other structures (amniotes)

16

pharynx & pharyngeal slits originally evolved as a?

filter feeding apparatus

17

in aquatic vertebrates, the pharynx is a?

respiratory organ (internal gills)

18

endostyle function? (protochordates & lamprey larvae)

for trapping food particle in the pharynx

19

endostyle function? (vertebrates & lamprey adults)

derives thyroid gland

20

endostyle evidence of homology?

endostyle & thyroid gland both secrete rare proteins w with iodine (rare in nature, t.f. homologous)

21

postanal tail function?

associated somatic musculature for propulsion in water (with great diversity of form and function across taxa)

22

"Urochordata"

"tunicates"

23

Urochordata notochord

restricted to tail in larva, and disappears during metamorphosis into adult

24

Urochordata ascidian larvae have?

tiny tadpoles with all 5 chordate synapomorphies (adults only retain pharyngeal slits & endostyle)

25

Urochordata ascidian larvae feed?

non-feeding, instead swim around and attach to solid object, metamorphoses into adult

26

Urochordata ascidian adult live?

most sessile (attached to substrate)

27

Urochordata ascidian adult feed?

filter feed with incurrent/excurrent siphons & endostyle

28

Urochordata ascidian adult reproduction?

hermaphroditic

29

"Cephalochordata"

"amphioxus" / "lancelets"

30

cephalochordata shape?

laterally compressed (elongate)