BIOL108 Lecture Notes - Lecture 29: Actinistia, Buccal Pumping, Tetrapod

• School: University of Alberta
• Department: Biology (Biological Sciences)
• Course: BIOL108
• Professor: Lien Luong

Document Summary

Named for their long, flexible rays that support fins. Class sarcopterygii lobe-finned fish; one of the 3 lineages of lobe-fin fish lungfish & tetrapods are sister taxa first lineage: actinistia & dipnoi. Shared traits: fleshy, muscular pectoral & pelvic fins. Supported by well-developed bony elements in the base. Many extinct species lived in brackish waters. Used fins to swim and walk underwater. Some modern fish use fins to walk (e. g. catfish)". Class actinistia (coelacanth) restricted to deep marine waters. Considered as a living fossil because they were thought to be extinct until 1938. Much more diverse in the fossil record; likely that they lived in shallow water & had lungs+gills the extant coelacanth has vestigial lungs) Class dipnoi (lungfish) restricted in freshwater lobe-fins. Gills and lungs two modes of gas exchange. Gulping air into lungs from water"s surface by lowering and raising the floor of their cavity they bury themselves in mud to survive dry periods.