Sharon Barton, age 12, of Shreveport.

Are fish the only animals that have gills?

Gills, of course, are organs for taking oxygen from water, much as our lungs take oxygen from the air. Many water‑dwelling creatures absorb oxygen directly into their cells and need no special organs to do the job. The more complex water‑dwellers, however, have gills of some kind though few of them are as well developed as the gills of a fish.

The clams and the oysters have gills of a sort, so do the crabs and the lobsters. The mud puppy has gills with frilly edges and during the early stage of his life, every amphibian animal absorbs his oxygen through a pair of gills.