EEMB 106 – Lecture 1 – What is a Fish? 1 1) What is a fish? 1) Aquatic–except (at times): grunion, walking catfish, etc.2)Vertebrates- except: hagfishes, lampreys (no vertebral centra) 3) Cold blooded / poikilotherms- except: some fast swimming fishes like tunas are partial homeotherms 4) Usually median and paired fins for locomotion and steering - except: eels 5) Scales - except in many derived fishes of Perciformes, e.g. blennies, jacks, etc. 6) Gills - extras: lungfishes (lungs), mudskippers (facultative skin respiration), other devices 7) Simple, one way heart, one pump with two simple chambers - only exception: African lungfish 8) Lateral line, “distant touch”, near-field pressure sensorSummary:• mostly aquatic vertebrate, • mostly cold-blooded, • usually with appendages developed as fins, • whose chief respiratory organs are usually gills aided by a simple two chambered heart, • and whose body is usually covered with scales and a lateral line. 2) Diversity of Forms Rover-predators: streamlined fishes, pointed head, terminal mouth, narrow caudal peduncle and forked tail, always on the move in search of prey, pursuit predators. E.g. trout, bass, tuna and mackerel, billfishes Lie-in-wait predators: fish eaters designed for capturing fast moving prey by ambush, elongate, streamlined forms, often with flattened heads, large, well-toothed mouths, tail fin is large, dorsal and anal fins far back on body E.g. pikes, barracudas, needlefishes, saury Surface-oriented fishes: typically small fishes, with dorsally directed mouths, flattened heads, large, dorsally directed eyes E.g. mosquitofishes, topminnows, killifishes, halfbeaks, flying fishes
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