EVERYDAY SCIENCE

Detailed explanation-1: -salminicola is the only known animal on Earth that does not breathe. If you spent your entire life infecting the dense muscle tissues of fish and underwater worms, like H. salminicola does, you probably wouldn’t have much opportunity to turn oxygen into energy, either.

Detailed explanation-2: -Unlike other fish with gills alone, lungfish can surface, take a breath and survive when other fish might be lacking air. In fact, much like many sea mammals, lungfish are obligate air breathers-they have to breathe air above water periodically to survive.

Detailed explanation-3: -A fish breathes by taking water into its mouth and forcing it out through the gill passages. As water passes over the thin walls of the gills, dissolved oxygen moves into the blood and travels to the fish’s cells.

Detailed explanation-4: -One species of salamander lacks lungs, so it breathes by absorbing oxygen through its skin and the roof of its mouth. The diving bell spider is able to breathe oxygen underwater by keeping air bubbles attached to its body with tiny, hydrophobic hairs.

Detailed explanation-5: -Fish take water into their mouth, passing the gills just behind its head on each side. Dissolved oxygen is absorbed from-and carbon dioxide released to-the water, which is then dispelled. The gills are fairly large, with thousands of small blood vessels, which maximizes the amount of oxygen extracted.