Is there an animal that can live indefinately on both land and underwater?
Terrapins (but strangely not marine turtles) can breathe underwater but have lungs. I didn’t used to believe this but all the terrapins I have kept spend the summer in the water and winters in the soil. Terrapins that cannot get to soil just sit at the bottom of the pond all winter and don’t move. They are equally able to feed in or out of the water. I can’t think of any other vertebrate that can do this. Being a naturalist not a biologist, I assume that as long as the skin is wet (it’s always damp soil) they can breathe through the skin (like frogs) because they have no gills. Although for some reason this fact has always bothered my common sense. But fact it remains. Perhaps another answer could enlighten me. (edit) Most crabs carry water with them when on land, land-crabs drown in water. There may be a species that can get away with it but generally crabs cannot live full time in both environments. (edit) Turtles (marine) have to come up for air.
