Fishes - central core of bones that form fully articulated...

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Fishes First fishes- bottom dwellers, with a jawless mouth underneath a flat head, and eyes on the upper surface (present day lamprey) I. Main Features A. Gills 1. Function: to extract oxygen dissolved in the water around them 2. Composed of fine filaments of tissue that are rich in blood vessels B. Vertebral Column 1. Function: as an internal skeleton (made of bone or cartilage) C. Single loop blood circulation 1. Blood is pumped from heart to gills 2. From gills, the oxygenated blood passes to the rest of the body, then returns to the heart 3. Fishes heart is composed of 4 sections: a. Sinus Venosus b. Atrium c. Ventricle d. Corus Arteriosus II. Main Classes of Fish A. Placodermi (Armored fishes) B. Acanthodii (Spiny fishes) C. Osteichthyes (Ray-finned fishes, Lobe-finned fishes) 1. Lobe-finned fishes a. Have paired fins that consist of a muscular lobe, supported by a
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Unformatted text preview: central core of bones that form fully articulated joint with one another b. Bony rays are present only at the tips of each lobed fin c. Muscles within each lobe can move the fin rays independently of one another (to the envy of bony fishes) d. Intermediate step: love-fined fishes (such as coelacanth, lungfish) e. Amphibians almost certainly evolved form the lobe-finned fishes. D. Chondrichthyes (Sharks, skates, rays) 1. Skeleton made of fortified cartilage (light and strong) 2. No gill cover 3. Reproduction: internal fertilization (usually, baby sharks are born alive) E. Myxini (Hagfishes) F. Cephalaspidomorphi (Lampreys) III. Bony fishes A. Skeleton made of bone (strong but heavy) B. Solution-Swim Bladder C. Have gill cover D. Reproduction: usually External Fertilization...
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