Chapter 6

Question 1

what are the two groups of chondricthes

Answer 1

gnathostomes and eugnathstomes

Question 2

what groups make up gnathostomes

Answer 2

placoderms, chondriches, and osteichthes

Question 3

what are the two major groups of chondrichthyans

Answer 3

holocephali and elasomobranchii

Question 4

what groups make up holocephali

Answer 4

ratfishes and chimeras

Question 5

what groups make up elasombranchii

Answer 5

sharks, skates, rays & fossils

Question 6

what are some characteristics of chondrichthyans

Answer 6

cartilaginous endoskeleton, placoid scales, large fatty liver, high blood urea, pelvic claspers, tooth whorl

Question 7

T/F is the dermal bone lost in chondrichythyans

Answer 7

True

Question 8

prismatic endoskeleton calcification, perichondral layers of cartilage are mineralized, crystalline calcification deposited on the surface

Answer 8

cartilaginous endoskeleton

Question 9

what is mineralized in bony fish

Answer 9

perichondral and endochondral

Question 10

dermal denticles of shark skin

Answer 10

placoid scales

Question 11

placoid scales closely resemble what in ostracoderms

Answer 11

odontes

Question 12

what minerals do placoid scales have

Answer 12

dentine and enamel

Question 13

placoid scales reduce what during swimming

Answer 13

drag

Question 14

what do the fatty liver and high blood urea levels maintain

Answer 14

buoyancy

Question 15

modified male pelvic fin serve as copulatory organs

Answer 15

pelvic claspers

Question 16

what type of fertilization for chondrichthyes and placoderms

Answer 16

internal fertilization

Question 17

series of replacement teeth

Answer 17

tooth whorl

Question 18

tooth whorl is the ancestral condition for what group

Answer 18

eugnathstomes

Question 19

how many days are the tooth whorl replaced in juveniles

Answer 19

8