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FISHES Agnatha Chondrichthyes Osteichthyes. General Characteristics Ectothermic Vertebrates Have scales Swim with fins Almost all exclusively aquatic.

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Presentation on theme: "FISHES Agnatha Chondrichthyes Osteichthyes. General Characteristics Ectothermic Vertebrates Have scales Swim with fins Almost all exclusively aquatic."— Presentation transcript:

1 FISHES Agnatha Chondrichthyes Osteichthyes

2 General Characteristics Ectothermic Vertebrates Have scales Swim with fins Almost all exclusively aquatic Filter oxygen from water over gills

3 Classes of Fish Agnatha – Jawless Fish Chondrichthyes – Cartilagenous Fish Osteichthyes – Bony Fish

4 Question #1: What is the name for a person who studies fishes? Ichthyologist

5 Early Fish Earliest - Filter feeders, no jaws, no fins Ostracoderms – jawless, heavy bony plates Lobe finned fishes – Coelocanths

6 Fish Anatomy

7 Fins Caudal – propels fish forward Dorsal – stabilizer Anal – stabilizer Pectoral – hold fish steady, maneuvering Pelvic – hold fish steady, maneuvering

8 Scale Types Cycloid – smooth surface, on bony fish – Carp – Salmon Ctenoid – teeth along ridge (rough to touch), on bony fish – Bass – Bluegill – Perch

9 Scale Types Placoid – Look like tiny teeth, feel like sandpaper, on cartilagenous fish – Sharks – Rays Ganoid – hard, interlocking, diamond-shaped, on primitive fish – Gar

10 Question #2: What is the purpose of a fish’s scales? Shield against injury, help to move through the water

11 Maintaining Buoyancy Swim bladder – Uses air – Most bony fishes – Can be used as a second “lung” Liver – Uses oil – Sharks – Most sharks must constantly swim to avoid sinking

12 Locomotion Use fins and body wall to push against water Forked tails reduce drag in the water Muscles in a zig-zag shape – Each contraction moves large parts of the body wall

13 Gills Obtain oxygen Give off carbon dioxide Most have an operculum Oxygen dropped into circulatory system pumped by 2-chambered heart

14 Gas Exchange Pump ventilation Ram ventilation Exchange of gases occurs in capillary network in gill lamellae; water and blood flow in opposite directions over lamellae = Countercurrent Exchange

15 Countercurrent Exchange System

16 Excretion and Osmoregulation Freshwater fishes – never drink – Lots of nephrons – Ions are reabsorbed Marine fishes – Drink constantly – Less blood is filtered – Water is reabsorbed

17 Senses Limited vision, focus by moving lens back and forth Olfactory receptors Magnetic receptors Touch

18 Sense (cont.) Hearing – sound conducted through skull Lateral line system – senses movement of other organisms around them Electroreception – sense electrical impulses generated by muscle twitches

19 Reproduction Oviparous (most fish) – Release eggs, young develop outside mom Ovoviviparous (some cartilaginous fishes) – Eggs remain inside mom – Eggs at a later stage of development before they are released Viviparous (a few sharks) – Young born alive

20 Class Agnatha Cartilagenous Simplest and oldest vertebrates Jawless No scales Scavengers or parasites Lamprey, hagfish

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22 Class Chondrichthyes Hinged jaw Paired fins Scales Muscles attached to skin, not skeleton Cartilagenous skeleton

23 Sharks Jaws not attached to brain case – Can protrude during attack – 20 tons per square inch for an 8’ shark Size varies (few inches to over 40 feet) Variable body shapes

24 Skates and Rays Wing-like pectorals Most live on sea beds Some have poison spines on backs or tails (stingrays)

25 Class Osteichthyes Largest group of fishes Skeleton made of bone and cartilage Hinged jaws Paired fins Hard, protective scales Covered gills (operculum)

26 Major Groups of Osteichthyes Subclass Sarcopterygii – Lobe-finned fishes (Coelocanth) – Lungfishes Subclass Actinopterygii – – Ray-finned fishes Bass Tuna Guppies


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