Lecture 6 Flashcards
What are the 5 features of osteichthyes?
Dermal bones, jaws, pectoral girdle, branchiostegial rays and gas bladders
On what part is the unique pattern of the jaws and braincase that is carried through to tetrapods?
Dermal bones
What are the maxila, premaxilla and dentary?
Maxilla/premaxilla: upper jaw & dentary: lower jaw
What does the extension of the dermal bones to the girdle form?
The operculum that covers the gills
What is the function of the branchiostegial rays?
They help expand the mouth
What is the Devonian period known as?
The age of the fishes
What did the first bony fishes resemble?
Acanthodians (spiny sharks)
What are sarcopterygians?
Lobe-finned fish
Describe the limbs of sarcopterygians
The rays of paired fins extended from the central shaft of the bones to support the fin web. Muscles on outside of the body wall
What is the name given to modern day bony fishes?
Teleosts
Describe the evolution of the mouth of Dipnoi (lungfish)
Tooth-bearing bones were lost, palatoquadrates fused to cranium, teeth scattered over palate & fused into ridges along lateral margins
Describe the evolution of the fins/bones of Dipnoi
Dorsal, caudal & anal fins merged into one, caudal fin became symmetrical. Skull bones went from many small to few large
True or false? Most fish are denser than water
True
Describe the embryonic development of the swim bladder
Outpocketings of the dorsal or ventral side of
the gut in the pharyngeal region
How do fish increase the surface area of the lungs?
Elaborating the walls (an alveolar lung) or by adding a second lobe
What do African Lungfish do during dry/summer months?
Aestivate, a period of dormancy to wait out the harsh conditions
What happens during an African Lungfishes aestivation?
They create a mucous-lined burrow with breathing holes. Metabolism and respiratory demands drop and muscle proteins are used as an energy source
What enamel-like element do stem actinopterygians have?
They have ganoine, unlike sarcopterygians which have cosmine
When did major morphological changes occur in time?
Towards the end of the Palaeozoic period
Name a few of the morphological changes that occurred towards the end of the palaeozoic period
Caudal fin lobes were nearly symmetrical, fewer rays in fins which increased flexibility and reduced dermal armour, supporting more versatile locomotion
When did the new lineage of Neopterygians emerge?
In the Permian period
Describe the jaws before and after the permian era
Cheek bones allowed little opening of the orobranchial chamber. After, short maxilla freed the cheek at posterior end.
What did the freeing of the cheek enable fish to do?
Swing out large mouth and increase suction
What enables sturgeons to respire when feeding?
A permanent opening at the top of the operculum for inflow, the spiracle isn’t used as much.
What is the long rostrum on the paddlefish innverated for?
It has ampullary organs to detect electric fields
What do gars and bowfins share?
The dorsal gas bladder that is vascularised and has a respiratory and buoyancy role. Heavy scaling too
What two things does the Weberian system connect?
Connects the swim bladder to the auditory system in fish
Describe the function of the Weberian system?
Sound vibrates the swim bladder, tripus (bone) pivots on the vertebra. Motion is transmitted by ligaments to the intercalarium and scaphum. Movement of scaphum compresses membranous labyrinth
What is the membranous labyrinth?
The inner ear
What are the two elements that receives the transmitted sound from the ligaments?
The intercalarium and the scaphum
