Chp 2: Phylum Hemichordata

Question 0

Subphylum cephalochordata

Answer 0

(Head cord)

Lancelets, amphioxus, “branchiostoma”

Question 1

Acorn worm

Answer 1

Pharynx w/slits
DHNC (only in collar)
Stomochord (homologous to notochord?? No.)
No post anal tail: gut tube goes all the way through animal

Question 2

Features of cephalochordata

Answer 2

All chordate characteristics of adults
And...
No vertebrae
Some cephalization
Asymmetry in myomeres

Question 3

Subphylum Urochordata

Answer 3

(Tail cord)

Tunicates or sea squirts

Question 4

Urochordata traits

Answer 4

Pharyngeal slits
Notochord only in tail of larvae
Filter feeders
Tunic of cellulose

Water flow: incurrent siphon (like plants), pharynx w/slits, atrium, excurrent siphon
*become sessile (lose tail)

Question 5

Subphylum vertebrata

Answer 5

(Craniata)
500 mya
50000 species (half are fish)

Question 6

Distinguishing characteristics of vertebrata

Answer 6

• cranium

- vertebrae

Question 7

Other vertebrate characteristics

Answer 7

• true brain, several divisions
• well developed eyes, organs of chemical perception
• extreme cephalization
• thyroid, pituitary (better reg. of hormones)
• solid liver
• hepatic portal blood system *
• gall bladder
• large body size

Question 8

Agnatha vs gnathostomes

Answer 8

Without jaw or with jaw

Question 9

Fish vs tetrapods

Answer 9

Fins or limbs

Question 10

Amniotes vs anamoniotes

Answer 10

Extra-embryonic membrane or not

Question 11

Class Agnatha

Answer 11

500 mya
Jawless fish (lamprey, hagfish)
*first vertebrate group
-most primitive body plan

Question 12

Subclass myxinoidea

Answer 12

hagfish

• no jaw, bone, or scales
• sucking mouth, scavengers
• mucous glands

Question 13

Subclass petromyzontida

Answer 13

Lamprey

• no jaw, bone, or scales
• rasping tongue, many are parasites

Question 14

Subclass “ostracodermi”

Answer 14

• first vertebrates, 500 mya
• first bone
• small filter feeders
• no jaw

Ostraco=shell
Derm=skin

Question 15

Class placodermi

Answer 15

400 mya; all extinct
Placo= plate
Derm= skin

Armored fish

• first jaw
• jaws from 1st pharyngeal arch
• paired appendages
• gas bladder (move around)

Question 16

Class Chondrichthyes

Answer 16

Sharks, rays, chimeras
-400 mya
Chondr= cartilage
Icthhyes= fish

• no bone in skeleton; skeleton fish
• evolutionary dead end-> nothing else evolved from it

Question 17

Class Osteichthyes

Answer 17

400 mya
Osteo= bone
Ichthyes= fish

-25,000 species: most diverse vertebrates
-bone in skull, vertebrae, fins, scales
*bony scales
Teleostomi= Osteichthyes

Question 18

Subclass actinopterygii

Answer 18

• ray finned fish
• fin muscles inside body wall
• teleosti (superorder) make up 95% of all living fish

Question 19

Subclass sarcopterygii

Answer 19

Ptery= wing

• lobe finned fish
• fin muscles are in the fin
• *point of evolution from fish to tetrapods**

3 major groups

• rhipidistians
• coelacanth
• lungfish (Dipnoi)

Question 20

Rhipidistians

Answer 20

-Sacropterygian fish gave rise to 1st amphibians

Feat:
Skull like amphibian, teeth like amphibian, bones of fin similar to tetrapods, choanae (internal nostrils)

Tiktaalik- intermediate fish fossils

Question 21

Coelacanth

Answer 21

“Living fossil”
Lobe finned fish
Discovered in 1938 by M. Courtenay Latimer

“Latimeria chalumna”

Question 22

Lungfish

Answer 22

Dipnoi

3 genera

• Gondwana distribution
• burrow + breathe air when transient pools dry up