Chordata

Question 1

Phylum

Answer 1

Chordata

Question 2

Subphylum

Answer 2

Vertebrata
Urochordata
Cephalochordata

Question 3

Urochordata

Answer 3

Tunicates

Molecular data suggests closer to vertebrata than cephalochordata

Question 4

Cephalochordata

Answer 4

Small marine animals that resemble vertebrata anatomically

Eg lancelet and amphioxus

Question 5

All chordate synapomorphies

Answer 5

Bilaterally symmetrical
Internal left-to-right body asymmetry
Pharynx (throat region containing pharyngeal slits -> filter feeding/resp.)

Question 6

Cephalochordata shared derived characteristics with vertebrata

Answer 6

Myomeres - blocks of striated fibres along sides of body
Similar circulatory system
Specialized excretory cells
Vertebrate-like tail fin
—> were considered sister groups to vertebrate but under dispute

Question 7

Chordate distinguished

Answer 7

Anatomically
Biochemically
Embryologically
By fossil record

Question 8

Chordate closely related to

Answer 8

Echinoderms (star fish and sea urchins)
Hemichordates (marine animals -> acorn worms)
Xenoturbellids (small marine wormlike forms)
Exact relationships unknown

Question 9

Deuterostomes

Answer 9

Greek for second mouth
Share unique embryological features
Egg division after fertilization
Larval forms

Question 10

Hemichordates

Answer 10

Acorn worms
Synapomorphs: (primitive)
Openings in pharynx region for filter feeding
-precursor to endostyle?

Question 11

Echinoderms

Answer 11

Modern echinoderms
-No pharyngeal slits
-Pentadactyl symmetry
Extinct echinoderms:
-Pharyngeal slits
-Bilateral symmetry
Molecular and developmental data indicate that they are closely related to chordata

Question 12

Ambulacraria

Answer 12

Molecular data unites echinoderms and hemichordates as ambulacraria, with xenoturbellids being sister to ambulacraria, and this 3 taxon lineage in turn being sister to chordata (vertebrata, cephalochordata and urochordata)