Lecture 29 Bony Fish

Question 1

what is cartilage?

Answer 1

flexible connective tissue with an abundance of collagenous fibres embedded in a chrondroitin sulfate

Question 2

what is fish?

Answer 2

paraphyletic group of aquatic craniates that use gills for respiration
- includes jawless fishes, cartilaginous fishes, bony fishes, excludes tetrapods

Question 3

what are bony fish?

Answer 3

• used to be –class osteichthyes – paraphyletic if restricted to fish
• now there are 3 classes of of bony fish

Question 4

what is clade osteichthyes

Answer 4

• bony fish

- modern classification includes all bony vertebrates in clade osteichthyans– MONOPHYLETIC

Question 5

what is clade osteichthyes

Answer 5

• “bony fish”
• modern classification includes all bony vertebrates in clade osteichthyans– MONOPHYLETIC
• includes bony fish AND tetrapods
• more suitable name is clade euteostomi – bony vertebrates

Question 6

what is the evolution of lungs and swim bladders?

Answer 6

• both are gas filled structures
• original simple lung modified into swim bladder in most extant bony fish
• swim bladder is homologous to the lungs – both arise as an outpocketing from the gut
• paired lungs - respiration
• single swim bladder - neutral buoyancy

Question 7

where did bony fish descend from?

Answer 7

ancestors living in brackish water that had simple lungs and gills

• simple lungs are dorsal outpocketing of gut filled with gas
• augumented gas exchange by gills

Question 8

how are swim bladders connected?

Answer 8

connected to the gut via pneumatic duct present in more primitive ray finned fish – connection lost in most ray-finned fish : closed swim bladder

Question 9

what are lungs and lung derivatives to bony fish?

Answer 9

synapomorphic for osteichthyans

Question 10

what are five characteristics of bony fish?

Answer 10

• ossified bony endooskeleton
• flat plate-like bony scales (rather than toothlike)
• operculum – single flap that covers gills
• swim bladder – gas exchange changes degree of inflation
• flexible fins
• external fertilization

Question 11

what are the 3 extant classes of bony fish?

Answer 11

ray fin:
- actinopterygiii

lobe-fin

• actinistia
• lungfish

Question 12

what are class actinopterygii?

Answer 12

• ray fin fish
• fins supported by long flexible rays for maneuvering and -defence
• nearly all familiar aquatic osteichthyans

Question 13

what are characteristics of lobe fin fish? (sarcopterygii)

Answer 13

• fleshy, muscular, pectoral and pelvic fins supported by bony elements in the base

Question 14

what are class actinistia?

Answer 14

• only one genus: ceolocanths
• restricted to deep marine waters
  “L

Question 15

what are class actinistia?

Answer 15

• only one genus: coelacanth
• restricted to deep marine waters
• “Living fossil”
• diverse in fossil record

Question 16

what are class dipnoi?

Answer 16

lung fish

have two modes of gas exchange: gills and lungs

• gulp air by lowering and raising floor of mouth cavity (buccal bump)
• 3 extant genera, freshwater habitats
• lungs are homologous to tetrapod lungs: both extend to ventral surface of the esophagus
  (swim bladders extend from dorsal esophagus)
• tetrapods are 1 of 3 surviving lineages of lobe fish