The Antarctic icefish (family Channichthyidae) lives in the extremely cold waters of the Southern Ocean. Unlike all other known vertebrates, icefish lack hemoglobin, the iron-rich protein that transports oxygen through the blood, leaving their blood translucent. To compensate for this absence, icefish have evolved several physiological adaptations: they possess exceptionally large hearts, a high volume of circulating blood, and a dense network of capillaries. Furthermore, icefish can absorb oxygen directly through their scaleless skin from the highly oxygenated polar waters. Despite these adaptations, their oxygen-carrying capacity is only about ten percent of that of typical red-blooded fish, restricting them to stable, cold environments where oxygen levels remain high.
Based on the text, what is true of the oxygen-carrying capacity of the Antarctic icefish's blood?
- It is about ten percent of that of typical red-blooded fish, which confines the icefish to cold environments with high oxygen levels.Cevap
- BIt is higher than that of other vertebrates because icefish absorb oxygen directly through their scaled skin.
- CIt allows the icefish to survive in any aquatic habitat regardless of stable temperatures.
- DIt is compensated for by a small heart that pumps blood rapidly through a sparse network of capillaries.