Osteichthyes/Actinopterygii

Question 1

Osteichthyes Traits

Answer 1

Skull with sutures, usually many bones
Dorsal nasal openings (2)
Usually a lung and swim bladder

Question 2

Coelacanthiformes

Answer 2

Hollow spine
Lobes fins articulate with pectoral/pelvic girdle
Diphycercal tail – 3 lobes (unique)
Cartilage and bone
Partially segmented vertebrae (like sharks)
spiral valve intestine (like sharks)
vertical head movement (like vertebrates)
External/internal nostrils
Unbranched fin ray (like sharks)
Highly conserved morphology
last fossil 70 million years ago
Head full of electroreceptors, often swim down head first
lung filled with fat for buoyancy
hyperosmotic (like sharks)
Immunoglobin genes (like sharks)
Ovoviviparous with large eggs (9cm) – 5-year gestation

Question 3

Discovery of the Coelacanth

Answer 3

Scientists first observed it in a fish market in South Africa (1938)
Another then found in an Indonesian fish market of different colour
Later identified as a distinct species
13 million year divergence between 2 lineages of Coelacanth

Question 4

Dipnoimorph

Answer 4

These are lungfish
excellent fossil record
always freshwater (south Africa, south America and Australia)
fossils are bony, extant are cartilaginous
unsegmented notochord (like sharks)
pectoral/pelvic girdle
gills as juveniles and lungs as adults
South African and South American have lungs, Australian have gills
Aestivate in dry season (bury in mucus until it rains), urea can concentrate 7x
spiral valve intestine
Sister to tetrapods

Question 5

Actinopterygii

Answer 5

Ray finned fishes
pectoral girdle attatched to scapular coracoid
no internal nostril
interopercular and branchiostegalis
lung/swim bladder
spiral valve absent

Question 6

Polypteryiformes

Answer 6

Many fins/wings
Reedfish
Cartilage
heterocercal tail
spiral valve intestine and spiracle
external gills in juvenile
inhale through mouth and exhale through spiracles
strong Paleozoic like scales

Question 7

Acipenseriformes

Answer 7

Sturgeon:
Bottom feeder
Largest freshwater fish
cartilage notochord/ossified skull
heterocercal tail and spiral intestine
interopercular absent

Paddlefish:
Electrosensor paddle
Mississippi river and Yangtze
heterocercal tail

Question 8

Lepisosteiformes

Answer 8

Gars
Bony scale – ganoid
3 branchiostegals, no interopercular
spiral valves
swim bladder
concave vertebrae
freshwater
heterocercal tail
very unflexible

Question 9

Amiiformes

Answer 9

bow fin
Slight heterocercal tail, and long dorsal fin
13-18 branchiostegals
amphicoelous vertebrae
reduced spiral valves
swim bladder can be lung
use dorsal fin to move to not disturb water
feed with large negative pressure