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Where we started… Myxiformes Petromyzontiformes Gnathostomata Gnathostomata Holocephali Elasmobranchi Sarcopterygii Actinopterygii Actinopterygii Acipenseriformes Semionotiformes Amiiformes Teleostei Teleostei Osteoglossomorpha Elopomorpha Clupeomorpha Ostariophysi Superorder: Ostariophysi • 64% of freshwater species! • Weberian apparatus Superorder: Ostariophysi • Schreckstoff signals • Schreckreakton Ostariophysi Gonorhynchiformes Cypriniformes Characiformes Siluriformes Gymnotiformes Gonorhynchiformes • 35 species • Have Schreckstoff signals • Don’t have Weberian apparatus – Do have modified first 3 vertebrate • Secondary loss of gas bladder Cypriniformes • Largest order- 2660 species! • Emergence of pharyngeal dentition Cypriniformes • Some are polyploidy – Linked with large size in minnows Catlocarpio siamensis Diploid #: 98 • Smallest freshwater fish in the world Paedocypris progenetica 7.99 mm Algae eaters • Gyrinocheilid – Water inhaled dorsally, exhaled ventrally • Suckers (Catostomidae) – Mostly benthic and live in lotic system feeding on algae and periphyton – Lake suckers (Chasmistes) planktivores with terminal mouths – Difficult for taxonomists Chasmistes cujus Family Cobitidae (Loaches) • • • • 110 species Benthic Size: from 2.5-12 inches Predominantly Eurasian, with the highest diversity in Southeast Asia. • Include popular aquarium species: – – – – – Kuhli Clown Skunk Loaches Golden Dojo *Weatherfish* Weatherfish (Misgurnus) • Reason for name: – Become restless when atmospheric pressure drops preceding a storm • Could be due to their air breathing abilities – Gulp atmospheric air and pass it as a bubble to the intestine, gaseous http://www.loaches.com/species-index/weather-loach-misgurnis-anguillicaudatus exchange then occurs • Balitorid river and hillstream loaches – Specialized for living in fast-flowing water • Streams of India and Southeast Asia – Have paired fins that oriented horizontally • Adhesive pads on ventral surfaces – Bodies depressed dorsoventrally – Mouths are ventral http://www.loaches.com/articles/hillstream-loaches-the-specialists-at-life-in-the-fast-lane Order Characiformes • • • • 1340 species 10 families are recognized Order has and is undergoing taxonomic revision 1150 Species found in South America, 200 in Africa, a few in Central America, one (Mexican Tetra) extends into Southwest Texas. • 10 species (including piranhas) have been introduced in the US • Characterized by: – Adipose fin – Well-armed mouths – Replacement Dentition – Ctenoid scales • Anatomically and Ecologically Diverse – Predators – Zooplanktivores – Scale eaters – Detritivores – Hebivores (feed on seeds, leaves and fruits) • Can be surface, water column, or benthic dwellers – Most prefer mid-water and many are in shoals • Large range of body sizes: – From 13-mm adult tetras to 1.5 m tigerfishes – Can be long and slender or deep-bodied and compressed http://www.aquafish.net/imgs/fish/silver-dollar-2.jpg • Popular Aquarium Fish: – – – – – – – Headstanders Spraying characins Freshwater hatchetfishes Blind characins Pencilfish Tetras Silver dollars http://www.aqua-fish.net/imgs/fish/common-hatchetfish-2.jpg • Most Primitive Characiforms – 100 species • African citharinids (Distichodus, Citharinus) – African characiforms also include 100 species of advanced alestiine characids – African origin for the order • Connection between Africa and South America – Prior to break up of Gondwanaland • Distribution of characiforms could be explained by vicariance – Reason for difference in species number between Africa (~200) and South America (1150) » South America more open niches? more speciation » Africa limited niches? limited speciation Subfamily Serrasalminae (Piranhas) • 60 Species – Some predatory, others scale-eating opportunist and specialist, and some herbivorous (Pacu and Silver Dollar) • Herbivorous species are important for two reasons: – Food fish – Seed dispersers • Because of dentition, can break the outer layer of the seed aiding in germination. • Needed by plants • Have undeserved bad reputation – Many cases didn’t actually kill the people • Drowned and piranhas picked at the dead body Piranha and Weatherfish Videos • http://www.youtube.com/watch?v=AqWzU Q8lp3M • http://www.youtube.com/watch?v=EiuNCH FU_Xg Questions • What are 3 advantages and 3 disadvantages to using Schreckstoff signals that you can think of? • Explain what has happened to create allow the evolution of pharyngeal dentition? • For what evolutionary purpose do you think the weather fish has developed sensitive to atmospheric pressure? • Why do you think larger ploidy numbers reflect larger organisms? • What is unique about Balitorid river and hillstream loaches? Picture Credits • http://www.loaches.com/species-index/weatherloach-misgurnis-anguillicaudatus • http://www.loaches.com/articles/hillstreamloaches-the-specialists-at-life-in-the-fast-lane • http://www.aqua-fish.net/imgs/fish/commonhatchetfish-2.jpg • http://www.aqua-fish.net/imgs/fish/silver-dollar2.jpg