Fish

The fish

The fish is an oviparous animals.The  fish is vertebrate. The parts of the fish aré:

Air bladder              Gill arches.              Shull.               Nostrils.                  Bulbous  arteriosus

Liver.                        Pyloric ceca.           Pectoral fin.    Intestine.                   Dorsal fins

Kidney.                   Ovary.                       Stomach.         Pelvic fin.               Lateral line

Caudal fin.              Anal fin              Abdominal pore.    Urogenital opening.    Anus

Respiration 

Most fish exchange gases using gills on either side of the pharynx. Gills consist of threadlike structures called filaments . Fish exchange gases by pulling oxygen-rich water through their mouths and pumping it over their gills. In some fish, capillera blood flows in the opposite direction to the water, causing countercurrent exchange . The gills push the oxygen-poor water out through openings in the sides of the pharynx. Some fish, like sharks and lampreys, possess multiple gill openings. However, bony fish have a single gill opening on each side.

Digestion 

In the stomach, food is further digested and, in many fish, processed in finger-shaped pouches called pyloric checa, which secrete digestive enzymes and absorb nutrients. Organs such as the liver and pancreas add enzymes and various chemicals as the food moves through the digestive tract.

Circulation 

The heart pumps the blood in a single loop throughout the body. In most fish, the heart consists of four parts, including two chambers and an entrance and exit.