FISH (Le Poisson)
DEFINITION:
Fish, as an aquatic animal is defined as a cold-blooded
vertebrate living in water, swimming with the help of fins and breathing with
the help of gills.
CHARACTER OF FISH-
- Fish possess a wide variety of external shapes and forms. The most common is the FUSIFORM (streamline). This shape is ideal as it offers minimum resistance for movement in water. All the fast swimming fish have this shaped body. For eg. mackerel, sardine, tuna, seer fish etc.
- Some fish have compressed body (COMPRESSIFORM), depressed body (DEPRESSIFORM) and some fish have cylindrical body shape (FILIFORM).
- The fish have fins (paired and unpaired) that aid them in swimming.
- The gills are used for breathing.
- Fish have a protective covering over their skin called scales, although some fish may be ‘naked’.
- Fish have eyes and smelling organs. The latter are located in nasal pits. The fish do not have external ears, although, inner ear system called labyrinth exists.
- Some of the fish also possess a swim bladder, which functions as a hydro-static organ.
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