FNR 24000 Lecture Notes - Lecture 27: Actinopterygii, Swim Bladder, Deep Sea
30 Nov 2018
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Document Summary
Over 32,000 species of fish have been described. Represent more than 50% of the vertebrate species in the world. They are the dominant life form in most aquatic systems. Many diverse adaptions to life, which has made them a favorite group of biologists. Anadromous-fishes which spend most of their lives in the sea and migrate to freshwater to breed (pacific salmon) Catadromous-fishes which spend most their lives in freshwater and migrate to the sea to breed (some freshwater eels) In both freshwater and marine fish groups, most species are found in the tropics. 44% live in less than 200 meters of water. Only 13% of all fish species are still being discovered. They either have or descended from ancestors that have scales or armor derived from. Lack limbs with digits (most have fins) dermal tissue. Living in water imposes some constraints on fishes-morphological, physiological, and ecological adaptations to life in water. Generate lift that overcomes the pull of gravity.
