What is a Fish? • Poikilothermic – body temperature is identical to surrounding water • Chordates – have developmental characteristics of all vertebrates • Appendages developed as fins • Chief respiratory organs are gills • Body generally covered with scales “A fish is an aquatic vertebrate with gills and with limbs in the shape of fins” (Nelson 1994) There are over 25,000 fish species, so there are exceptions to these general characteristics.
Fish vs. Fishes “This tank is full of fish.” “The ocean is full of fishes.”
Functional Morphology in Fishes Functional Morphology – “the study of form and structure in animals as related to the functions of the various body parts” W.A. Gosline, 1971
Acceleration Specialists –Adaptations for Ram Feeding Thick Caudal Peduncle Flexible Body Large Gape Maxilla may or may not be excluded from gape Posterior-placed Median Fins
Lunate Tail Finlets Caudal Keels Fusiform Body Narrow Caudal Peduncle Cruising Specialists – Adaptations for Sustained Swimming Terminal Mouth bluefin tuna – Thunnus thynnus
Maneuvering Specialists – Adaptations for Suction Feeding Laterally Compressed Body Small Gape Maxilla Excluded From Gape Laterally Positioned Pectoral Fins
Adaptations for Bottom Dwellers Barbels Dorso-ventrally Compressed Body Inferior Mouth
Adaptations for Surface Dwellers Superior Mouth Counter-color Shading
Fish Identification: Color … ? Fathead Minnow (Pimephales promelas)
Fish Identification : Patterns white bass (Morone chrysops) - stripes yellow perch (Perca flavescens) - bars northern pike (Esox lucius) - spots
Fish Identification : Patterns red drum (Sciaenops ocellatus) - eye spot white shark (Carcharodon carcharias) -counter-color shading
Fish Identification: Fins Spiny Dorsal Fin (protection, steering, braking) Soft Dorsal Fin (forward propulsion, steering, braking) Caudal Fin (forward propulsion) Anal Fin (forward propulsion) Pectoral Fin (braking, steering, propulsion) Adipose Fin (Ictaluridae, Salmonidae) Pelvic Fin (braking, steering) Pelvic fins in thoracic position (derived state) Pelvic fins in abdominal position (more primitive)
Fish Identification: Shapes Forked Fins vs. Rounded streamlined Body vs. deep Scales vs. diamond round superior inferior terminal Mouth vs. vs.
Tadpole Madtom Northern Pike Brook Stickleback Golden Shiner Fish Identification : Unique Features Teeth Barbels Scales Lateral line