मछली पानी में कैसे साँस लेती है

Video narration

Aap hawa mein saans lete hain, lekin paani ke bheetar machhli ko saans lene layak oxygen kahan se milti hai? Paani ko dekhkar lagta hai ki shayad machhli paani se hi saans leti hogi. Asal baat yeh hai: machhli paani se oxygen nahi banati. Woh paani mein pehle se ghuli oxygen leti hai. Paani munh se bheetar jaata hai aur galphadon, yaani sir ke paas ke saans lene wale hisson, se hokar baahar nikalta hai. Is raaste mein paani mein ghuli oxygen khoon mein pahunch jaati hai. Phir khoon ise shareer ke alag-alag hisson tak le jaata hai. Saath hi, carbon dioxide khoon se paani mein nikalti hai aur paani ke saath baahar chali jaati hai. Paani ka bahna isi liye zaroori hai: wahi oxygen galphadon tak laata hai. To machhli ko saans ki oxygen paani mein ghuli milti hai, aur use lene ka raasta galphade hain.