Vertebrate/Agnathans Lecture

Question 1

vertebrate synapomorphies (4)

Answer 1

• size
• speed & mobility
• capacity for food location/capture (predation) & digestion
• metabolic rate

Question 2

vertebrate musculo-skeletal modifications

Answer 2

endoskeleton (cartilaginous or bony)

Question 3

vertebrate endoskeleton helps

Answer 3

• greatly reduce limits on body size - muscles outside of skeleton so muscle size less limited
• less energy input into skeleton since it grows w/ animal (molting unnecessary)
• “energy if the currency of life”

Question 4

cartilaginous skeleton reflects

Answer 4

original condition (bony skeleton evolved later w/in vertebrates)

Question 5

cartilaginous skeleton found in

Answer 5

• all vertebrate embryos (fast growth & flexible)

- adult hagfishes, lampreys, sharks

Question 6

vertebrate musculo-skeletal modifications increased

Answer 6

complexity of myomeres (segmented body muscles)

• V shaped in cephalochordates
• W shaped in vertebrates

Question 7

vertebrate physiological modifications: pharynx

Answer 7

functions as respiratory structure

• muscularization of the pharynx
• vascularization of the pharyngeal arches (gills (arches have bony components = increases structure strength)

Question 8

vertebrate physiological modifications: gut

Answer 8

evolved from functioning by ciliary action to muscular action (like pharynx) with use of accessory glands (liver, pancreas, etc)

Question 9

vertebrate physiological modifications: circulatory system

Answer 9

enhanced gas & nutrient transport

- 3 chambered heart, erythrocytes, Hb

Question 10

2 other vertebrate physiological modifications:

Answer 10

• protected tripartite

- paired sensory organs (associated with predatory habitat)

Question 11

vertebrate duplication of Hot genes: (2)

& both are!!!

Answer 11

• Neural crest (ectodermal) (produce most of cranium, pharyngeal skeleton, Schwann cells)
• Ectodermal placodes (produce olfactory epithelium, eye lens, inner ear epithelium)
• vertebrate synapomorphies!!!

Question 12

Hox genes found in what organisms?

Answer 12

all segmented organisms

Question 13

Hox genes are:

Answer 13

ancient genes that give developmental identity to body segments (ex: limbs)

Question 14

how many copies of Hox genes genes found in invertebrates?

Answer 14

1

Question 15

More copies of Hox genes happen by?

Answer 15

gene duplication events

Question 16

Hox genes may have facilitated:

Answer 16

evolution of increased complexity of segments in vertebrates

Question 17

“Agnatha”

Answer 17

“no jaws”

Question 18

Agantha =

Answer 18

ostracoderms (extinct) + hagfishes & lampreys (extant)

Question 19

Agnatha is monophyletic or paraphyletic?

Answer 19

paraphyletic

Question 20

Agnathan skeletons are

Answer 20

fibrous/cartilaginous

no internal ossification (bone growth)

Question 21

Agnatha have notochord?

Answer 21

Yes

Question 22

Agnatha lack

Answer 22

paired fins & scales

Question 23

Agnatha gills?

Answer 23

pore-like gill openings

Question 24

Agnatha fertilization?

Answer 24

internal

Question 25

Myxini aka

Answer 25

“hagfishes”

Question 26

Myxini characteristics

Answer 26

• rudimentary skull & no vertebrae
• one pair semicircular canals
• eyes probably degenerate (ex: reduced-derived)
• produce amazing slime

Question 27

Myxini development?

Answer 27

no larval stage
feeding body (prey on invertebrates/scavenge fish & whale falls)

Question 28

Cephalaspidomorphi aka

Answer 28

“lampreys”

Question 29

Cephalaspidomorphi characteristics: (4)

Answer 29

• suction mouth w/ keratinized teeth
• simple cartilaginous vertebrae
• 2 pairs semicircular canals
• well developed eyes

Question 30

Cephalaspidomorphi habitat

Answer 30

marine or FW

Question 31

Cephalaspidomorphi development

Answer 31

• Cephalaspidomorphi larvae “ammocoetes” hatch & filter feed in FW
• metamorphosis into parasitic or non-feeding adults
• parasitic adults migrate to ocean or lake & parasite
• return to FW (streams) to breed

Question 32

Extinct Agnathans

Answer 32

Ostracoderms (named for bone in dermis “shell skin”)

Question 33

Ostracoderms bony plates are

Answer 33

likely homologous to dermal bones of jawed vertebrates (gnathostomata)