EEMB 106 – Lecture 1 – What is a Fish?
1) What is a fish?
except (at times): grunion, walking catfish, etc.
except: hagfishes, lampreys (no vertebral centra)
Cold blooded / poikilotherms
except: some fast swimming fishes like tunas are partial homeotherms
Usually median and paired fins for locomotion and steering
- except: eels
- except in many derived fishes of Perciformes, e.g. blennies, jacks, etc.
- extras: lungfishes (lungs), mudskippers (facultative skin respiration), other devices
Simple, one way heart, one pump with two simple chambers
- only exception: African lungfish
Lateral line, “distant touch”, near-field pressure sensor
mostly aquatic vertebrate,
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
: 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
: 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
: typically small fishes, with dorsally directed mouths, flattened heads,