Lecture 22

Question 1

Class Osteichthyes

Answer 1

bony fishes, paraphyletic when restricted to fish, monophyletic when all other bony vertebrates included

Question 2

6 characteristics of bony fishes

Answer 2

1. bony endoskeleton
2. flat plate-like bony scales
3. operculum
4. lungs or structures derived from lungs
5. highly flexible fins
6. external fertilization common

Question 3

bone

Answer 3

a connective tissue consisting of living cells held in a rigid matrix of collagen fibers embedded in calcium salts

Question 4

operculum

Answer 4

single protective flap that covers gill opening

Question 5

lungs in bony fish

Answer 5

ancestors had simple lungs as well as gills, original lung modified to swim bladder in extant bony fish

Question 6

swim bladder

Answer 6

air sac that controls buoyancy of fish, gas exchange between blood and bladder changes degree of inflation of bladder, can ‘float’ at the depth they desire

Question 7

fins in bony fish

Answer 7

highly flexible (rather than stiff fins of chondrichthyans), for propulsion and for maneuvering

Question 8

bony fish reproduction

Answer 8

1. male and female release gametes
2. fertilized eggs sometimes cared for by parents
3. sometimes young fish cared for as well
4. internal fertilization and ovoviviparity also occur

Question 9

3 classes of bony fish

Answer 9

1. Actinopterygii (>99%)
2. Actinistia
3. Dipnoi

Question 10

Class Actinopterygii

Answer 10

ray-finned fishes, long flexible rays that support fins

Question 11

Class Actinistia

Answer 11

lobe-finned osteichthyans, coelacanths only extant genus, viviparous, restricted to deep marine waters, fleshy muscular pectoral and pelvic fins supported by bony elements in the base, well developed lung in embryos of extant coelacanths

Question 12

Class Dipnoi

Answer 12

lungfishes, lobe-finned osteichthyans, have gills and lungs, buccal pump

Question 13

buccal pump

Answer 13

gulp air into lungs from water’s surface by lowering and raising floor of mouth cavity

Question 14

bony fish and economy

Answer 14

1. fishing resulted in collapse of many fish stocks
2. fish farming may help to some extent
3. no-catch reserves allow replenishment of stock outside of reserve

Question 15

Tetrapoda

Answer 15

1. lobe-finned osteichthyans
2. vertebrates with two pairs of sturdy, skeleton supported limbs with digits
3. clearly lack gills in adult state

Question 16

Tiktaalik rosea

Answer 16

375 MYA, fishy features (scales, fins without digits, gills+lung) and tetrapod features (neck, ribs, wrist bones,
eyes on top of head)

Question 17

tetrapod digits

Answer 17

thought to be derived from ancestors with 5 digits per limb, ancient semi-terrestrial vertebrates had >5

Question 18

2 groups of extant tetrapods

Answer 18

1. Amphibia

2. Amniota

Question 19

Amphibia

Answer 19

monophyletic, frogs, toads, salamanders, and caecilians, thin permeable skin, use buccal pump to inflate lungs, eggs lack shell, external fertilization, many species have aquatic larvae (gills) and terrestrial adults (lungs)

Question 20

3 orders of living amphibians

Answer 20

1. anura
2. urodela
3. caecilians

Question 21

Order Anura

Answer 21

frogs and toads, hind legs modified for jumping, lack tail in adult stage, toads differ from frogs in having poison glands behind eyes

Question 22

Order Urodela

Answer 22

salamanders and newts, have tails as both larvae and adults, sometimes paedogenetic, salamanders walk rather than jump (less energetically efficient than positioning legs beneath body)

Question 23

global amphibian decline

Answer 23

parasitic flatworms (platyhelminths may be increasing because their intermediate hosts, snails, do better in organically polluted waters)