Osteichthyes (Bony Fish) Flashcards
What are the two main lineages of Osteichthyes?
Sarcopterygian (Lobe finned) and Actinopterygian (ray finned)
What belongs to the ray finned group Chondrostei?
Sturgeons (transitionary species), Paddle fish and Neopterygii (Teleosts)
List common features of Neopterygii?
Homocercal (symmetrical) tail, Elasmoid scales made of 2 thin layers, vertebrae are complexity ossified, premaxillary/maxillary bones of upper jaw are movable, highly manoeuvrable fins, operculum consists of four bones.
What is the function of the operculum?
Covers the gills.
How have advances in gill movement been achieved?
Branciostegal rays allows pumping of water across gills, interbranchial septum is reduced.
What is the function of the gill lamellae?
Used to increase the surface area in contact with the environment to maximise gas exchange (both to attain oxygen and to expel carbon dioxide) between the water and the blood.
What is the difference between Physotomous fish and Physoclistous fish?
The dorsal air bladder is attached to the oesophagus in Physostomous fish (less advanced).
how are some Teleosts adapted to extreme environments?
can control their temperature by behavioural means, can survive in very acidic environments and still stake up sufficient ions to survive.
What is unique of Antarctic fish?
Have lost the genes for haemoglobin as cold water holds more oxygen, have developed antifreeze proteins and production of glycerol to stop their serum from freezing.
What are Iteraparous fish?
Reproduce multiple times during life, spawning once/several times per year.
What are Semelparous fish?
Reproduce only once in their life.
