Vertebrates - Gnathostomes (Exam 3)

Question 1

what are gnathostomes?

Answer 1

living jawed vertebrates; “gnatho” = jaw & “stome” = mouth

Question 2

what are jaws?

Answer 2

hinged structures - to grip food and slice them

Question 3

jaws evolved from what?

Answer 3

skeletal rods that used to support pharyngeal slits (gills)

Question 4

what happened to the rest of gill slits that didn’t become jaws?

Answer 4

remained as gills - the major site of respiratory gas exchange

Question 5

what is the lateral line system?

Answer 5

in aquatic gnathostomes - organs in row on side of body- sensitive to vibrations in water around them

Question 6

what are Chondrichthyes?

Answer 6

“cartilage fish”- skeleton of cartilage and not bone - were first major vertebrates w/ jaws

Question 7

what animals are in class Chondrichthyes?

Answer 7

sharks- rays

Question 8

what fins do sharks have / their functions?

Answer 8

dorsal fins (stabalize)- tail fin (go forward)- & paired pectoral and pelvic fins (maneuvering)

Question 9

what are dermal denticle and what class has them?

Answer 9

tooth-like scales for speed and protection; Chondichthyes

Question 10

how do sharks get continuous water flow from mouth to gills?

Answer 10

some have to swim all the time - others have muscles of jaws and pharynx that pump water over their gills

Question 11

how do sharks feed?

Answer 11

largest are suspension feeders that eat plankton - most are carnivorous and use jaws and teeth

Question 12

how do sharks make up for short digestive track?

Answer 12

spiral valve - corkscrew ridge that increases surface area and slows down passage of food

Question 13

what senses do sharks have?

Answer 13

no eardrums - body receives and transmits to hearing organ; good vision (no colors); nostrils for smelling only not breathing

Question 14

how do sharks reproduce?

Answer 14

sexual - some oviparous- most viviparous; have cloaca which is single opening for reproductive- digestive- and excretory tracts

Question 15

what are key differences of rays vs sharks?

Answer 15

rays are mostly bottom-dwellers and flat shape

Question 16

what are Osteichthyes?

Answer 16

class of gnathostomes - have ossified (body) endoskeleton; aka fishes

Question 17

what is the bony flap that protects gills in fish?

Answer 17

operculum

Question 18

how does water move in fish?

Answer 18

in mouth- through pharynx- out btwn gills; moves by operculum and surrounding muscles contracting

Question 19

what structures in sharks and fish give them buoyancy?

Answer 19

oil in liver (sharks) and air filled swim bladder (fish)

Question 20

how is skin different in fish and sharks?

Answer 20

fish- flattened body scales vs sharks- tooth-like scales

Question 21

how do fish reduce drag while swimming?

Answer 21

slimy mucous released by skin glans

Question 22

what are Actinopterygii (ray-finned fishes)?

Answer 22

group of osteichthyans; most of the fish we know are in this group; protein for humans

Question 23

what are Sarcopterygii (lobe-finned fishes)?

Answer 23

have rod-shaped bones surrounded by muscle

Question 24

what are tetrapods?

Answer 24

have limbs and feet

Question 25

what are Coelacanths (s.c. Actinistia)?

Answer 25

of lobe-finned fishes (sarcopterygii); thought to be extinct but one caught 90 years ago - “living fossil”

Question 26

what are lungfishes (s.c. Dipnoi)

Answer 26

of lobe-finned fishes (sarcopterygii); gulp air at surface into lungs; use gills for gas exchange

Question 27

what group of fish evolved into tetrapods?

Answer 27

lobe-finned (Sarcopterygii)

Question 28

what is clade urodela?

Answer 28

salamanders - “tailed ones”; side-by-side bending to move if terrestrial

Question 29

what is clade anura?

Answer 29

frogs; move easier than salamanders

Question 30

are toads and frogs the same?

Answer 30

toads are frogs that have leather skin / other adaptations to live better on land

Question 31

what adaptations protect frogs?

Answer 31

skin glands secrete mucous that tastes bad or is poisonous; bright colors

Question 32

what is clade Apoda?

Answer 32

Caecilians; legless- nearly blind

Question 33

why are Caecilians tetrapods?

Answer 33

evolved from legged ancestor - lost to reduce energy use and burrow better

Question 34

what are amphibians?

Answer 34

means both life = tadpole is larval (aquatic) herbivore and after metamorphosis is carnivore; not all necessarily do both

Question 35

where do amphibians typically lay eggs?

Answer 35

in water or moist land areas

Question 36

how do amphibians reproduce?

Answer 36

fertilization is external; eggs don’t have a shell so can dehydrate quickly- or lay a lot so some survive- or need parental care

Question 37

why do amphibians usually live in damp areas?

Answer 37

need moist skin for gas exchange

Question 38

why do some amphibians house eggs on their back or in mouths/stomach?

Answer 38

protect from predators and prevent them from drying out