Question

classify the respiration and transportation of fish?

Answer 1

Respiration in fish takes place mainly through gills although some fishes can also breathe air directly. Gills are present in both side of pharynx. Gills contain filaments which have capillary network that provide large surface area for exchange of gases. Lungfish also use a pair of lungs for breathing in addition to the gills. Some fish such as eels take air directly through skin, buccal cavity etc. when out of water or in oxygen depleted water.
Circulation or transportation in fishes occur through two-chambered heart which pump blood and it is called closed-loop circulatory system. Heart pump the blood through capillaries to gills and tissues of the body.