Lecture 17

Question 1

How to get better, stronger, faster?

Answer 1

All of vertebrate life is descendent from fish

Question 2

Chordates

Answer 2

• Cephalochordata
• Urochordata
• Vertebrata

Question 3

Unique characteristics of Chordates

Answer 3

• Dorsal hollow nerve cord
• Notochord
• Muscular post-anal-tail

Question 4

Pharyngeal slits (pouches)

Answer 4

• located on lateral surface of the head
• seem to be an ancestral trait in deuterostomes
• lost in echinoderms
• in vertebrates, pharyngeal tissue supported by arches
• evolved into jaw structure, inner ear parts

Question 5

Function of Pharyngeal slits

Answer 5

• filter feeding in cephalochordates (lancelet) and urochordates (tunicates)
• respiration in vertebrates (water coming in mouth passes through slits, O2 CO2 can be exchanged across a respiratory surface = gills, gills located btwn slits, supported by cartilaginous arches)

Question 6

Gill slits and gill arches

Answer 6

• pharyngeal slits = gill slits
• bars btwn the slits = gill arches (bone or cartilage, gill filaments are on the gill arches)
• Bony fishes have 4 pairs of gill arches
• Each arch has pairs of gill filaments
• Bony fishes also have a gill cover (operculum)

Question 7

Gill filament

Answer 7

• thin, vascularized, high surface area
• Blood vessels flow through gill arches
• capillary beds in gill filaments; gas exchange
• filament epithelium is one cell thick (1-2 um)

Question 8

Countercurrent exchange

Answer 8

• water& blood flow in opposing direction
• max the exchange of of materials across osmotic gradients as opposed to cocurrent flow
• minimizing heat loss
• ensures that concentration gradients are maintained

Question 9

Fish circulatory system

Answer 9

• closed system
• arteries (away from heart) ventral aorta–> arterioles –> capillaries –> venules (to heart) –> veins (dorsal aorta)
• u can’t accelerate the blood after it goes in the capillary bed, flows passively
• human (not fish) have:
  (pulmonary circuits = heart –> lungs –> heart; systemic circuit = heart –> body –> heart, 4 chambered heart)

Question 10

Fish heart = 2 chambers and folded

Answer 10

• strong, muscular pump
• ventrally located
• maintains blood flow
• 2+ chambers (auricle/atrium and ventricle)
• one way valves so no backflow

Question 11

Vertebrates - Characteristics

Answer 11

• Axial skeleton
• Appendicular skeleton
• Closed circulatory system
• Organs suspended in coelom

Question 12

Axial skeleton

Answer 12

Vertebrates

• Cranium (skull)
• Vertebral column (spine)
• Ribs

Question 13

Appendicular skeleton

Answer 13

• Pectoral girdle (2 pectoral fins)

- Pelvic gridle (2 pelvic fins)

Question 14

Closed circulatory system

Answer 14

• Ventral heart

Question 15

Organs suspended in coleom

Answer 15

important

Question 16

Fishes precious

Answer 16

Fish make up half of chordate diversity

Question 17

Vertebrates, but not gnathostomes

Answer 17

• “Jawless fishes” (Agnathans)
• 2 groups: lampreys and hagfish
• no jaws
• cartilaginous skeleton
• notochord present
• Gill slits
• no paired fins
• no swim bladder
• no scales

Question 18

Hagfish (mixinoidea)

Answer 18

• Scavengers
• Knot tying - tie themselves in a knot to pull against
• mucous production - a lot of it
• Osmotic concentration same as seawater
• used for leather products

Question 19

Lamprey (petromyzontoidea)

Answer 19

• no jaw (“oral disc” instead [Can suck and latch onto something]
• very distinct larval form (ammocyete)
• adults of many species are parasitic on fishes

Question 20

Jaws: Gnathostomes

Answer 20

Jaw

• not present in early fishes and present day agnathans
• formed by fusion of gill arches
• teeth evolved from scales in mouth
• Greatly improved ability to feed and diversify

Question 21

Paired fins

Answer 21

• on pectoral and pelvic limb girdles
• enabled more active swimming
• used for steering, stabilizing and lift

Question 22

Gnathostomes

Answer 22

• “Cartilaginous fishes” (Chondrichthyes)
• jaws
• paired fins
• scales
• no swim bladder
• predators, scavengers- filter feeder
• Ex. Manta ray, big skate, sharks

Question 23

Gnathostomes

Answer 23

• “Body fishes” (osteichthyes)

- largest vertebrate group

Question 24

Swim Bladder

Answer 24

• flotation device
• enables neutral buoyancy
• gas regulated by gland in bladder or by swallowing/burping air

Question 25

Two groups of bony fish

Answer 25

- Ray finned fishes (actinopterygians) [teleosts, most fishes] - lobe finned fishes (sarcopterygians) [lungfish, coelocanths - thought to be extinct, we descended from these, closest fish relatives)

Question 26

A cool teleost

Answer 26

Deep sea angler fish - 700-100 m - Bioluminescent lures - phermones - males are "parasitic" on females

Question 27

How to get better, stronger faster?

Answer 27

1. get more oxygen, gills, heart 2. Get that skeleton on the inside 3. Jaws 4. Paired fins