Sunday, November 20, 2016

HSEB zoology notes | General characteristic of Pisces

The general characteristics of Pisces are as follows :




1.  Habitat : They are completely aquatic found in marine or freshwater. They are cold blooded (poikilothermic) animals.

2.  Body form : They have streamlined body or boat shaped and laterally compressed. Body is covered by cycloid or placetoid scales.

3.  Locomotion : Locomotion in Pisces is performed by paired fins (pelvic, pectorial fins) and unpaired fins (anal , dorsal , caudal fins).

4. Respiration : They respire through gills. Gills may or may not be covered by operculum.

5. Swim bladder may or may not be present and they two chambered heart.

6. Reproduction system : Sexes are separate in them (diocoius) and some show sexual dimorphism like cartilaginous fish and some don't like bony fish. Those who show sexual dimorphism have clasper for transferring sperm to female genital tract.

7. Development is direct and fertilization in Pisces is both internal and external.






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