Lecture 25

Question 1

What are the 4 synapomorphies of chordata

Answer 1

1. Notochord
2. Dorsal, hollow nerve cord
3. Pharyngeal Clefts
4. Muscular, post-anal tail

Question 2

What are Cephalochordata

Answer 2

Lancelets

Question 3

What are urochordata

Answer 3

Tunicates
-have all 4 synapomorphies as larvae but not as adults
-adults go through metamorphosis so chordate characteristics disappear
-

Question 4

What are Myxini

Answer 4

hagfish
-protect themselves by exuding slime
-mouth surrounded by tentacles

Question 5

What are Petromyzontida

Answer 5

lampreys
-eyes with lenses, but no jaws or limbs
-notochord surrounded by cartilaginous tube
-Skelton made of cartilage (not hard)

Question 6

What are Gnathostomes

Answer 6

jawed fish
-gnath=jaw
-stoma=mouth
-two pairs of fins

Question 7

How did Gnathostomes develop jaws

Answer 7

-modifications of skeletal rods that were supported by pharyngeal slits
-arose from gill arch

Question 8

What are Chondrichthyes

Answer 8

sharks, rays, & chimeras
-early jawed fish
-cartilaginous fishes

Question 9

Characteristics of Chondrichthyes

Answer 9

-detect changes in electrical fields via pores
-nostrils function for smelling & gas exchange
-detect vibrations in the water

Question 10

How do sharks reproduce

Answer 10

-sperm transfer through copulation
-internal fertilization