Before this stage they are so small that there is no need for gills to extract oxygen from the water.

These include a gill-like apparatus in the tail that extracts oxygen from water.

Hydrogen gas can also be used to extract oxygen from the lunar regolith, although the process is not very efficient.

They are capable of breathing under water, since their skin cells extract oxygen directly from the water.

We developed just enough lung area to be able to efficiently extract oxygen from a 20% mixture.

His lungs strained to extract oxygen from the thin, frigid air and the pain drove him to greater effort.

Like other fishes, sharks extract oxygen from water as it passes over their gills.

Equipment was also developed to extract oxygen from sea water.

Cells extract oxygen from blood as it circulates through the body.

Fish breathe by extracting oxygen from water through their gills.