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Flashcards in Gnathostome Lecture Deck (64)
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1

Gnathostome aka

"jaw mouth"

2

Gnathostome key synapomorphies

- jaws
- appendages (fins)

3

Other Gnathostome synapomorphies

- 3 pairs semicircular canals
- notochord partially/completely replaced by centra
- neural & hemal arches extend from notochord (surface are a for muscle attachment & more maneuverability)
- horizontal septum divides trunk musculature divided into epaxial (dorsal) & hypoxia (ventral) portions for increased muscular coordination)

4

jaws =

skeletal elements (bone or cartilage) that support borders of mouth

5

jaws derived...

evolutionarily & developmentally from pharyngeal arches (neural crest)

6

jaws first appeared in which fishes?

placoderms

7

benefits of jaws (2)

- permitted more effective predation
- increased size of prey that would be captured

8

ancestral condition of pharyngeal arches

cartilaginous elements around pharyngeal slits

9

jaws provide

structural support for gills

10

1st pharyngeal arch =

mandibular arch
- palatoquadrate (dorsal)
- mocker's cartilage (ventral)

11

2nd pharyngeal arch =

hyoid arch
- hyomandibula (dorsal element)

12

paired appendage benefit

- greater body control in 3D space
- increased surface are (fins) allows for greater speed & maneuverability

13

True or false: about 1/3 of described extant chordate species are fishes

False (it's 1/2)

14

Major clades of Gnathostomes: (5)

- Placodermi - placoderms (extinct)
- Aconthodii (extinct)
- Chondrichthyes - sharks, ray, chimaeras
- Osteichthyes - bony fishes (paraphyletic)
- Tetrapoda

15

Placodermi

Most basal gnathostome lineage (extinct)

16

Subclass Chondrichthyes

sharks, rays chimaeras

17

Chondrichthyes skeleton?

cartilaginous

18

Elasmobranchii is part of

Chondrichthyes

19

Elasmobranchii animals = body styles

sharks (fusiform) & rays (depressed)

20

Elasmobranchii tail

heterocercal (swim "lift")

21

Elasmobranchii intestine valve

spiral valve in intestine
- increases time food in intestine
- increased SA for diffusion

22

Elasmobranchii fertilization

internal fertilization via clasper on male

23

Clade Neoselachii part of

Subclass Elasmobranchii

24

Sublcass Holocephali animals

chimaeras/ratfishes

25

Holocephali diverged from

earliest shark lineage (sister lineages to shark)

26

Holocephali habitat

marine/deep ocean

27

Lateral Line System structure & function

grooves/canals w/ neuromasts - mechanoreception (sensing mechanical disturbances)

28

Lateral Line System senses

water movements + directionality of course
- used for navigation & predation/evasion

29

Electroreception happens by

ampullae: (of Lorenzini, for example) specialized sensory cells detected electric current in water
- gives off electric potentials during neuromuscular activity

30

electroreception role

in prey detection