Cartilaginous fish

Question 1

what % of total marine life is jawed fish (gnathastoma)

Answer 1

96.1%

Question 2

name kingdoms most recently evolved (from oldest to newest)

Answer 2

fishes, reptiles, mammals, birds

Question 3

what are the general challenges of life in qwater?

Answer 3

oxygen, temp, pressure

Question 4

why is oxygen a challenge in water

Answer 4

20-40X LESS ABUNDANT (SO gills need to pump 20-40x harder), constrains morphology, monstains MR

Question 5

why is energy a challenge in water

Answer 5

high conductivity- constrains energetics + thermoregulation (insulation required)

Question 6

why is pressure a challenge in water

Answer 6

800x more dense (difficult to maintain buoyancy)

Question 7

what are the 2 subclasses of chondrichthyes

Answer 7

holocephali (chimaera) + elasmobranchi (sharks + skates)

Question 8

what are the 2 elasmobranch clades

Answer 8

selachii (sharks) + batoidea (skates + rays)

Question 9

general characteristics of chondrichthyes

Answer 9

cartilaginous skeelton, neurocranium w/ no sutures, placoid scales, dermal denticles (change w/ buoyancy), elevatedurae in blood, short gut w/ spiral valve, weird jaw suspension, internal fetilisation

Question 10

sensory systems unique to chondrichthyes

Answer 10

electroreception (lemellae of lorenzini), spiricles, 5-7 gill slits, nicitating membrane

Question 11

oviparity in chondrichthyes

Answer 11

protected in a kerantinised egg, no parental care, widely used (chimaera have corkscrew egg)

Question 12

ovoviviparity in chondrichthyes

Answer 12

eggs are retained in egg yolc sac (placental viviparity), uterine cannabilism, live birth through cloaca

Question 13

3 types of ovoviviparity

Answer 13

single ovipariati (1 egg case retained short), multiple oviparity (multiple indivs birthed when developed), sustained single oviparity (retain 1 egg until developed ie. catfish)

Question 14

viviparity in chondrichthyes

Answer 14

live birth

Question 15

examples of viviparity in chondrichthyes

Answer 15

dusky sharks: ~10 pups/ lifetime, slow reproduction, 20mn gestation

Scallop hammerhead: uterine cannabilsm to feed embryos to prevent cannabilsm

Question 16

characteristics of holocephali (GHOST SHARKS)

Answer 16

oviparous, special clasper on forehead, 3 fused tooth plates, veneous spine, 4 gills

Question 17

characteristics of elasmobranchs

Answer 17

5-7 gill opening, non-fused upper jaw, M lack cephalic clasper

Question 18

characteristic of batoids

Answer 18

dorsoventrally flattened, enlarged pec fin contiguous with head

Question 19

squalomorphii orders (lantern sharks)

Answer 19

6-gill sharks, squaliformes, bramble, angel, saw

Question 20

geleomorphii orders

Answer 20

heterodontiforms, carpet, mackeral, ground

Question 21

orders in batoidea

Answer 21

skats, electric rays, guitarfish, rays

Question 22

examples of convergent evolution in chondrichthyes

Answer 22

rays + dorso-ventrally flattened sharks, angel sharks using crypsis (same as rays), sawshark vs sawfish

Question 23

cranial kinsesi

Answer 23

mobility of upper jaw

Question 24

5 types of jaw suspension

Answer 24

holostylic (fixed), amphistylic (upper jaw w/ 2 ligaments), orbitostylic (ligament to orbital socket), hyostylic (ligament to cranium), euhyosylic (no ligament)

Question 25

what types of chondrichthyes have holostylic jaw suspension

Answer 25

chimaeras

Question 26

why are chimaera though to not radiated as much

Answer 26

limited jaw suspension (holostylic) limiting diet adaptation

Question 27

what chondrichthyes have amphistylic jaw

Answer 27

squalomorphs + fossil sharks

Question 28

what chondrichthyes typivslly have obitostylic jaws

Answer 28

most squalomorphs

Question 29

what chondricthyes have hyostylic jaws

Answer 29

galeomorphs

Question 30

what senses d chondrichthyes use (from furthest to closest)

Answer 30

olfaction, hearing, lateral line, vision, electroreception, touch/tast

Question 31

how do chondrichthyes maintain bouyancy

Answer 31

have high urea % maintinaing osmotic balance w/ seawater

Question 32

why are sharks caught in fisheries

Answer 32

morpholigcal features increase bycatch (long pectoral fins), many have no set TACs, huge demand for sharks (medicinal)

Question 33

has sharks become less endangered from 2014 to 2021

Answer 33

increased to 33% (from 25%) in VU, EN, C, but reduced to 13% DD (so learning more)

Question 34

why are chondrichthyes important for conservation

Answer 34

3% of fish diversiy but 15% order diversity, highest amount of ESI, very vulnerable to threats (life histories make them easy to catch)

Question 35

edge score

Answer 35

evolutinoary distinctiveness

Question 36

what sp. has the highest edge score

Answer 36

large-tooth sawfish