Definitions are dangerous, since exception are often viewed as falsification of the statement (Berra, 2001). Exceptions to the definitions above fo not negate them but instead give clues to adaptations arising from particularly powerful selection pressures. Hence loss of scales and fins in many eel-shaped fishes tell us something about the normal function of these structures and their inappropriateness in benthic fishes with elongate body.
Deviation from "normal" in these and other exceptions are part of the lesson that fishes has to teach us about evolutionary process."Fish" is singular and plural for a single species. Fish were the first vertebrates.
Raw data
rdfs:comment
Definitions are dangerous, since exception are often viewed as falsification of the statement (Berra, 2001). Exceptions to the definitions above fo not negate them but instead give clues to adaptations arising from particularly powerful selection pressures. Hence loss of scales and fins in many eel-shaped fishes tell us something about the normal function of these structures and their inappropriateness in benthic fishes with elongate body.
Deviation from "normal" in these and other exceptions are part of the lesson that fishes has to teach us about evolutionary process.
"Fish" is singular and plural for a single species. Fish were the first vertebrates.
commentSource
Helfman, G., Collette, B. B., Facey, D. E., & Bowen, B. W. (2009). The diversity of fishes: biology, evolution, and ecology. John Wiley & Sons.
Berra, T. M. (2001). Freshwater fish distribution. Academic Press.
Nelson, J. S. (2006). Fishes of the World. John Wiley & Sons.
definition
A fish is an aquatic vertebrate with gills and with limbs in the shape of fins (Nelson 2006).
"A poikilothermic, aquatic chordate with appendages (when present) developed as fins, whose chief respiratory organs are gills and whose body is usually covered with scales", (Berra 2001, p. xx)
A typical fish is ectothermic, has a streamlined body for rapid swimming, extracts oxygen from water using gills or uses an accessory breathing organ to breathe atmospheric oxygen, has two sets of paired fins, usually one or two (rarely three) dorsal fins, an anal fin, and a tail fin, has jaws, has skin that is usually covered with scales, and lays eggs. ("Fish." Wikipedia. Accessed January 4, 2016. https://en.wikipedia.org/wiki/Fish.)
definitionSource
Helfman, G., Collette, B. B., Facey, D. E., & Bowen, B. W. (2009). The diversity of fishes: biology, evolution, and ecology. John Wiley & Sons.
