WILD 3580 1st Edition Lecture 8 Outline of Last Lecture I Trends in Evolutionary Change II Speciation Mechanisms Outline of Current Lecture I Geologic Eras II Fish III Fish Forms IV Fish Evolution and Classification V Ostracoderm Characteristics VI Superclass Gnathostomata Current Lecture I II III Geologic Eras Geologic deposits give us a measurement of time Relative age of fossils the deeper the organisms are found the older it is Eras are divided into periods which are subdivided into epochs o Age of Fishes Devonian Period of the Paleozoic Era Fish The first vertebrates Aquatic vertebrates that have fins limbs and gills some exceptions 28 000 living species high in diversity make up about half of all vertebrates o Been around the longest o 70 of Earth is water o Can adapt quickly 58 marine 41 freshwater 1 diadromous move between salt and fresh water as a part of their normal life cycle Fish Forms 1 Anadromous spend most of their lives in the ocean but return to freshwater to reproduce Ex Salmon a Semelparous reproduce once during life These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute IV V VI b Iteroparous reproduce multiple times during life 2 Catadromous spend most of their lives in freshwater and return to the ocean to reproduce Ex Eels 3 Amphidromous move between fresh and salt water during some part of life not for reproduction a Feeding overwintering Fish Evolution and Classification Probably arose from the Lancelet or Amphioxus Have a boney head shield Historically called Ostracoderms shell skinned o 2 classes Pteraspidomorphi ancestors to modern hagfish and Cephalaspidomorphi ancestors to modern lampreys Ostracoderm Characteristics Bony armor Pineal organ light sensing organ Hypocercal tail No paired fins or true jaws Probably bottom dwellers and filter feeders Superclass Gnathostomata Vertebrates with jaws Arose independently did not have a common ancestor with jawless fish Consequences of having jaws o Allows a greater diversity of foods o Defense against predators
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