Chordate Origins and Basal Groups

Question 1

5 characters shared by all chordates

Answer 1

notochord, dorsal hollow nerve cord, pharyngeal slits, postanal tail, and endostyle

Question 2

notochord

Answer 2

flexible, rodlike structure running along dorsal side of body, first part of endoskeleton to form, allows for muscle attachment

Question 3

dorsal hollow nerve chord

Answer 3

above notochord, produced by infolding of ectoderm on dorsal side

Question 4

pharyngeal gill slits

Answer 4

openings leading from pharynx to the rest of the body, formed by ectoderm and edoderm coming together to form a hole

Question 5

endostyle

Answer 5

thyroid gland, originally for filter feeding, created iodinated proteins, secretes the thyroid gland

Question 6

invalid group of Chordates containing Cephalochordata and Tunicata

Answer 6

Phylum Protochordata

Question 7

subphylum of Protochordata known as lancelets

Answer 7

subphylum Cephalochordata

Question 8

general characters of subphylum Cephalochordata

Answer 8

small, look like finless fish, live in shallow coastal waters, basal to all chordates

Question 9

method of feeding for Cephalochordates

Answer 9

oral hood with ciliated tentacles pulls water into buccal cavity and pharynx, food gets trapped in mucus secreted by the endostyle on pharyngeal bars

Question 10

circulatory system of Cephalochordates

Answer 10

closed circulatory system with no heart or blood (cilia move fluids around body)

Question 11

respiratory system of Cephalochordates

Answer 11

respiration occurs through body surface

Question 12

reproduction of Cephalochordates

Answer 12

separate sexes and external fertilization

Question 13

subphylum of Protochordata containing sea squirts and salps

Answer 13

subphylum Tunicata

Question 14

general characters of Tunicates

Answer 14

globally distributed, live in mostly shallow waters, adults are highly simplified filter feeders, mostly sessile, can be solitary or colonial

Question 15

feeding method of Tunicates

Answer 15

feed like a sponge, pumping water through their body and trapping food

Question 16

characteristics of Tunicate larva

Answer 16

larvae have all 5 characters of a chordate, metamorphosis makes it sessile and simple (larva resembles tadpoles)

Question 17

3 classes of subphylum Tunicata

Answer 17

Ascidiacea, Thaliacea, and Appendicularia

Question 18

class of Tunicata known as sea squirts

Answer 18

class Ascidiacea

Question 19

characters of class Ascidiacea

Answer 19

sessile filter feeders, have an incurrent and excurrent siphon

Question 20

method of feeding for Ascidiaceans

Answer 20

water drawn into the incurrent siphon is forced through pharyngeal slits where food particles are trapped on the endostyle

Question 21

circulatory system of Ascidiaceans

Answer 21

not a circuit; heart switches directions of flow every few beats

Question 22

reproduction in Ascidiaceans

Answer 22

mostly hermaphroditic with sperm shot out of excurrent siphon and taken in through incurrent siphon (avoid self-fertilization)

Question 23

3 growth forms of Ascidiaceans

Answer 23

solitary, gregarious (live with buddies), and colonial

Question 24

class of Tunicata known as salps

Answer 24

class Thaliacea

Question 25

characters of class Thaliacea

Answer 25

free-floating pelagic Tunicates with siphons directed anterior to posterior to aid in locomotion, can form huge colonial tubes

Question 26

class of Tunicata known as larvaceans

Answer 26

class Appendicularia

Question 27

characters of class Appendicularia

Answer 27

free-floating pelagic Tunicates, paedomorphic, construct a “house: aoround mouth, anus, and endostyle to trap food, houses are discarded regularly

Question 28

paedomorphic

Answer 28

retaining larval chordate characteristics into adulthood